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Conversion of CO2 to Carbonates Catalyzed by Ionic Liquids under Mild Conditions
Meng, Xianglei
Publication date:2019
Document VersionPublisher's PDF, also known as Version of record
Link back to DTU Orbit
Citation (APA):Meng, X. (2019). Conversion of CO
2 to Carbonates Catalyzed by Ionic Liquids under Mild Conditions. Technical
University of Denmark.
DTU Chemical EngineeringDepartment of Chemical and Biochemical Engineering
Conversion of CO2 to Carbonates Catalyzed by Ionic Liquids under Mild Conditions Xianglei Meng
Conversion of CO2 to Carbonates Catalyzed
by Ionic Liquids under Mild Conditions
Center for Energy Resources Engineering
Department of Chemical and Biochemical Engineering
Technical University of Denmark
DK-2800 Kgs. Lyngby, Denmark
II | P a g e
Conversion of CO2 to Carbonates Catalyzed
by Ionic Liquids under Mild Conditions
Ph.d. Thesis
By
Xianglei Meng
Supervisor: Nicolas von Solms (DTU)
Co-supervisors: Xiaodong Liang (DTU)
Suojiang Zhang (IPE)
Xiangping Zhang (IPE)
May, 2019
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Preface
This project is supported by Department of Chemical and Biochemical Engineering
(KT) Technical University of Denmark (DTU) and Institute of Process Engineering (IPE),
Chinese Academy of Sciences.
I would like to first thank my supervisors Nicolas von Solms and Suojiang Zhang to
give me this good opportunity to learn from both DTU and IPE. My main supervisor
Nicolas is one of the nicest and easy-going people I have ever seen. Thanks for your kind
help and understanding, and I would like to express my sincere respect to you.
My co-supervisors from IPE, Suojiang Zhang and Xiangping Zhang, I am grateful
for your help and for your care and attention in both study and life. Your attitudes to
scientific research have always encouraging me to learn from you and improving myself.
My co-supervisor from DTU, Xiaodong Liang, you really gave me so much help, and
solved me a lot of problems. I would like to thank your kind help.
My colleagues at CERE, DTU. I would like to thank you all. It’s really the happiest
time of my life to work with you at CERE. Specially Yingjun Cai and Meng Shi, thank you
for the great help in both life and study, we look like a family.
My colleagues at IPE. I would like to thank for all your kind help on my research study.
To my co-operators Ting Song and Zhibo Zhang, thank you for supporting and
encourage.
My wife, thank you for supporting and understanding me.
Finally, I would like to thank for the financial support of National Key R&D Program
of China (2018YFB0605802).
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Abstract
The utilization of CO2 as a raw material is always a hot topic in both academic and
international industry. The synthesis of five-membered cyclic carbonates by cycloaddition
of CO2 with epoxides is one of the typical feasible routes. Ionic liquids (ILs) have been
widely reported in the cycloaddition reaction of CO2, because of the unique features such
as high thermal and chemical stability, easy recyclability, and tunable properties.
Although most of the ILs catalyst systems show a good yield to produce carbonates, high
energy inputs such as high temperatures and/or high CO2 pressures are always needed.
For energy saving reasons, we designed a series of functional ILs and used them to
catalyze the cycloaddition reaction of CO2 with epoxides under mild conditions. The major
work and results for this dissertation are summarized as follows:
1. Carboxylic acid-based ionic liquids (CAILs) were designed and synthesized. They
displayed temperature-dependent dissolution−precipitation transitions in propylene
carbonate (PC) by controlling the chain length of the carboxyl group. It was found that it
could be attributed to the temperature-controlled hydrogen-bond formation/broken
between the CAILs components and PC by NMR investigations and DFT calculations.
Such a unique phase behaviour was successfully utilized for the cycloaddition reaction of
CO2 with epoxides. Due to the activation of epoxide assisted by the hydrogen bond, the
optimal ILs could show a 92% yield of PC within 20 min and quickly precipitate out from
a homogeneous system at room temperature for easy recycling. The reversible phase
transition phenomenon supplied an efficient way to combine activity and recovery of
homogeneous catalysts, which is a benefit for energy-saving and industrial applications.
2. An efficient 1,8-diazabicyclo- [5.4.0] undec-7-ene (DBU) based bifunctional protic
ionic liquids (DBPILs) was easily prepared by acid-base reaction at room temperature.
DBPILs that composed by alkoxy anion, protic acid and nucleophilic groups exhibited
high activity for the coupling reaction of CO2 and epoxide under mild conditions. As a
metal free catalyst, the best DBPILs showed a 92 % yield of products within 6 hours at
30 oC and 1bar CO2 without any solvents and co-catalysts. And it could afford carbonates
in good yields with broad epoxide substrate scope and CO2 from simulated flue gas (15%
CO2/85% N2). IR spectrum and DFT studies were carried out to invest the mechanism of
the cycloaddition reaction. The results showed that the DBPILs could activate both CO2
and epoxide by the alkoxy anion and powerful hydrogen-bonding, which was well
consistence with experiments.
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3. DBU based ionic liquids containing aluminium (DILA) catalyst was synthesized
based on dissociating feature of proton from DBPILs. DILA was used as a single-
component and solvent-free catalyst for the conversion of CO2 to cyclic carbonates with
epoxide at mild conditions. DILA showed a catalytic activity of 94% within 6 h in catalyzing
the reactions of CO2 with epoxides at 30 oC and 1 bar CO2, because of the efficiently
activating epoxides by the aluminum ions. The effect parameters such as temperature,
reaction times and catalyst dose were investigated. Furthermore, DILA was found
suitable for a broad epoxide substrate scope and could be easily recycled at least four
times without obviously loss of activity.
4. A series of cross-linked poly (vinylimidazole/butyl acrylate) ionic liquids
membranes (PVBILs) were prepared and used as highly efficient heterogeneous
catalysts for fixation of CO2 with epoxide at mild conditions. PVBILs could show
comparable activities in the coupling of epoxide and CO2 with the traditional homogenous
catalysts, because of the activity of CO2 and “homogenous-surroundings” caused by
swellable properties. Swelling behaviour was studied and found to be consistent with the
experimental results of the catalytic activity. The dependence of conversion yield on
catalyst dose, reaction temperature and time were investigated. The best PVBILs could
show a 90% yield of carbonate within 24 hours at 50 oC and 1 bar of CO2.
5. A series of metalloporphyrin ionic liquids (MPILs) that combine the advantages of
ionic liquid and porphyrin were designed and synthesized by one step method. The
structure and surface appearance of these BPILs were investigated. These BPILs
catalysts have multiple active sites and a good capacity of visible light absorption due to
the advantages of functional ionic liquids and metal porphyrin part, thus can reduce the
energy inputs greatly by using the visible light. They were successfully used as a
photocatalyst in cycloaddition reaction of CO2 with epoxide to produce carbonate at room
temperature and 1 bar pressure under irradiation of a visible light.
Key words: Ionic liquids, Epoxide, Conversion of CO2, Mild conditions, Cyclic carbonate.
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Resumé
Udnyttelsen af CO2 som råmateriale er altid et varmt spørgsmål i både den
akademiske verden og den internationale industri. Syntesen af cykliske carbonater ved
cykloaddition af CO2 med epoxider er en af de typiske gennemførlige reaktionsruter.
Ioniske væsker (IL'er) er blevet rapporteret bredt i cykloadditionsreaktionen af CO2 på
grund af de unikke egenskaber som høj termisk og kemisk stabilitet, let
genanvendelighed og justerbare egenskaber. Selvom de fleste IL-katalysatorsystemer
viser et godt udbytte for at fremstille carbonater, er der altid brug for høje energiindgange
såsom høje temperaturer og / eller høje CO2-tryk. Af energibesparende årsager designer
vi en række funktionelle IL'er og anvendte dem til at katalysere cykloadditionsreaktionen
af CO2 med epoxider under milde forhold. Arbejdet og resultaterne for denne afhandling
er opsummeret som følger:
1. Carboxylsyrebaserede ioniske væsker (CAIL'er) blev designet og syntetiseret. De
viste temperaturafhængige opløsnings-udfæ ldningsovergange i propylencarbonat (PC)
ved at kontrollere kædelængden af carboxylgruppen. Det blev fundet, at det kunne
henføres til den temperaturstyrede hydrogenbindingdannelse / bruddet mellem CAILs-
komponenterne og PC'en ved NMR-undersøgelser og DFT-beregninger. En sådan
enestående faseadfæ rd blev med succes udnyttet til cykloadditionsreaktionen af CO2
med epoxider. På grund af aktiveringen af epoxid assisteret af hydrogenbindingen kunne
de optimale IL'er vise et 92% udbytte af PC inden for 20 minutter og hurtigt udfæ lde fra
et homogent system ved stuetemperatur for nem genbrug. Fænomenet om reversibel
faseovergang leverer en effektiv måde at kombinere aktivitet og genopretning af
homogene katalysatorer, hvilket er en fordel for energibesparende og industrielle
anvendelser.
2. En effektiv 1,8-diazabicyclo- [5.4.0] undec-7-en (DBU) -baseret bifunktionel
protisk ionisk væske (DBPIL) blev let fremstillet ved syrebase-reaktion ved
stuetemperatur. DBPIL'er, der består af alkoxyanion, protisk syre og nukleofile grupper,
udviser høj aktivitet for koblingsreaktionen af CO2 og epoxid under milde betingelser. Som
en metalfri katalysator viste de bedste DBPIL'er et 92 % udbytte af produkter inden for 6
timer ved 30 °C og 1bar CO2 uden nogen opløsningsmidler og co-katalysatorer.
Carbonatudbyttet var godt i et bredt concentrationsområde for epoxid substrat og CO2 fra
simuleret røggas (15% CO2 / 85% N2). IR spektrum og DFT undersøgelser blev udført for
at undersøge mekanismen i cycloaddition reaktionen. Resultaterne viste, at DBPIL'erne
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kunne aktivere både CO2 og epoxid ved alkoxyanionen og kraftig hydrogenbinding, i
overensstemmelse med forsøgene.
3. DBU-baserede ioniske væsker indeholdende aluminium (DILA) katalysator blev
syntetiseret baseret på DBPIL'ernes evne til at fraspalte en proton. DILA blev anvendt
som en enkeltkomponent og opløsningsmiddelfri katalysator til omdannelse af CO2 til
cycliske carbonater med epoxid ved milde betingelser. DILA viste en katalytisk aktivitet
på 96% inden for 6 timer ved katalysering af reaktionerne af CO2 med epoxider ved 30 °C
og 1 bar CO2 på grund af aluminiumionernes effektive aktivering af epoxiderne.
Effektparametre såsom temperatur, reaktionstider og katalysatordosis blev undersøgt.
Desuden blev DILA fundet egnet i et bredt concentrationsområde af epoxidsubstrat og
kunne let genvindes mindst fire gange uden åbenbart tab af aktivitet.
4. En serie af poly (vinylimidazol / butylacrylat) ioniske væskemembraner (PVBIL'er)
med tvæ rbindinger blev fremstillet og anvendt som højeffektive heterogene katalysatorer
til fixering af CO2 med epoxid ved milde betingelser. PVBIL'er kunne vise
sammenlignelige aktiviteter i koblingen af epoxid og CO2 med de traditionelle homogene
katalysatorer på grund af aktiviteten af CO2 og "homogene omgivelser" forårsaget af
svulmeegenskaber. Opsvulmingen blev undersøgt og fundet at væ re i overensstemmelse
med de eksperimentelle resultater af den katalytiske aktivitet. Afhængigheden af
konverteringsudbytte af katalysatordosis, reaktionstemperatur og tid blev undersøgt. De
bedste PVBIL'er kunne give et 90% udbytte af karbonat inden for 24 timer ved 50 °C og
1 bar CO2.
5. En række metalloporphyrin ioniske væsker (MPIL'er), der kombinerer fordelene ved
ionisk væske og porfyrin, blev designet og syntetiseret ved en-trins metode. Disse BPILs
struktur og overfladeudseende blev undersøgt. Disse BPIL-katalysatorer har flere aktive
steder og har en god kapacitet for absorption af synligt lys. På grund af fordelene ved
funktionelle ioniske væsker med metalloporfyrin, kan energibehovet reduceres kraftigt
ved at anvende synligt lys. De blev med succes anvendt som en fotokatalysator i
cykloadditionsreaktion af CO2 med epoxid til fremstilling af carbonat ved stuetemperatur
og 1 bar tryk under bestråling af synligt lys.
Nøgleord: Joniske væsker, Epoxid, Omdannelse af CO2, Svage betingelser, Cyclisk
carbonat.
VIII | P a g e
Contents
Preface ........................................................................................................... III
Abstract .......................................................................................................... IV
Resumé .......................................................................................................... VI
Contents ...................................................................................................... VIII
Chapter 1. Introduction ................................................................................ 11
1.1 Ionic liquids ............................................................................................................ 11
1.1.1 Definition of ionic liquids ............................................................................ 11
1.1.2 Categories of ionic liquid ........................................................................... 12
1.2 Utilization of CO2 ................................................................................................... 13
1.3 Conversion of CO2 to cyclic carbonates ............................................................ 14
1.3.1 Routes to synthesis cyclic carbonates .................................................... 14
1.3.2 Catalysts for synthesis cyclic carbonates ............................................... 15
1.3.3 Cycloaddition of CO2 and epoxide under mild conditions .................... 27
1.4 Research contents ................................................................................................ 31
Chapter 2: Temperature-Controlled Reaction-Separation for Conversion
of CO2 to Carbonates with Functional Ionic Liquids Catalyst ........................ 33
2.1 Introduction ............................................................................................................ 33
2.2 General information .............................................................................................. 35
2.3 Experimental section ............................................................................................ 36
2.3.1 Main equipment .......................................................................................... 36
2.3.2 Synthesis of catalysts ................................................................................ 36
2.3.3 Characterization of the catalysts .............................................................. 36
2.3.4 1H NMR and 13C NMR of Products .......................................................... 38
2.3.5 Procedure of the cycloaddition reaction of CO2 with propylene oxide 39
2.3.6 Reaction equipment ................................................................................... 40
2.4 Results and discussion ........................................................................................ 40
2.5 Conclusions ........................................................................................................... 52
Chapter 3: Efficient Transformation of CO2 to Cyclic Carbonates by
Bifunctional Protic Ionic Liquids under Mild Conditions ................................. 53
3.1 Introduction ............................................................................................................ 53
3.2 General information .............................................................................................. 55
3.3 Experimental section ............................................................................................ 56
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3.3.1 Synthesis of catalysts ................................................................................ 56
3.3.2 Characterization of the catalysts .............................................................. 58
3.3.3 Procedure of the cycloaddition reaction of CO2 with epoxide .............. 58
3.3.4 Recycle experiment .................................................................................... 58
3.3.5 Characterization of the catalysts and cyclic carbonates ...................... 59
3.4 Results and discussion ........................................................................................ 63
3.4.1 Activities of various catalysts .................................................................... 63
3.4.2 Effect of reaction conditions ...................................................................... 64
3.4.3 Catalytic activity of epoxides with simulated flue gas and SO2 ........... 66
3.4.4 Catalytic activity to various epoxides ....................................................... 67
3.4.5 Recycling of the catalyst ............................................................................ 68
3.4.6 Studies of reaction mechanism ................................................................ 71
3.4.7 Probable mechanism for fixation of CO2 with epoxide ......................... 73
3.5 Conclusions ........................................................................................................... 74
Chapter 4: Aluminium-containing Ionic Liquid for Cycloaddition of CO2
with Epoxides under Mild Conditions ................................................................ 76
4.1 Introduction ............................................................................................................ 76
4.2 Experimental section ............................................................................................ 78
4.2.1 General information .................................................................................... 78
4.2.2 Synthesis of catalysts ................................................................................ 78
4.2.3 Characterization .......................................................................................... 79
4.2.4 Procedure of the cycloaddition reaction of CO2 with epoxide .............. 83
4.2.5 Recycle experiment .................................................................................... 83
4.3 Results and discussion ........................................................................................ 83
4.3.1 Activities of various catalysts .................................................................... 83
4.3.2 Effect of reaction conditions ...................................................................... 85
4.3.3 Catalytic activity to various epoxides ....................................................... 87
4.3.4 Recycling of the catalyst ............................................................................ 88
4.3.5 Probable mechanism ................................................................................. 88
4.4 Conclusions: .......................................................................................................... 89
Chapter 5: Poly Ionic Liquids Based Membranes as Highly Efficient
Heterogeneous Catalyst for Conversion of CO2 to Cyclic Carbonate under
Mild Conditions ...................................................................................................... 90
5.1 Introduction ............................................................................................................ 90
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5.2 Experimental section ............................................................................................ 91
5.2.1 General information .................................................................................... 91
5.2.2 Synthesis of catalyst used in this study. .................................................. 92
5.2.3 Characterization .......................................................................................... 94
5.2.4 Procedure of the cycloaddition reaction of CO2 with epoxide .............. 96
5.2.5 Swelling ratio measurement...................................................................... 96
5.3 Results and discussion ........................................................................................ 97
5.3.1 Activities of various catalysts .................................................................... 97
5.3.2 Effect of reaction conditions ...................................................................... 99
5.3.3 Catalytic activity to various epoxides ..................................................... 100
5.3.4 Recycling of the catalyst .......................................................................... 101
5.3.5 Probable mechanism ............................................................................... 102
5.4 Conclusions ......................................................................................................... 102
Chapter 6: Biological Porphyrin Ionic Liquids as Photocatalysts for
Conversion of CO2 to Carbonates ................................................................... 104
6.1 Introduction .......................................................................................................... 104
6.2 General information ............................................................................................ 105
6.3 Experimental section .......................................................................................... 106
6.3.1 Synthesis of catalysts .............................................................................. 106
6.3.2 Characterization of the catalysts ............................................................ 107
6.3.3 Procedure of the cycloaddition reaction of CO2 with epoxide ............ 107
6.3.4 Characterization of the catalysts and cyclic carbonates .................... 108
6.4 Results and discussion ...................................................................................... 110
Conclusions and future work .................................................................... 112
References................................................................................................... 114
APPENDICES ............................................................................................. 139
The Cartesian coordinates for Chapter 2 ............................................... 139
The Cartesian coordinates for Chapter 3 ............................................... 157
Abbreviation list ........................................................................................... 178
Peer reviewed journal articles .................................................................. 181
Conference presentations ......................................................................... 181
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Chapter 1. Introduction
1.1 Ionic liquids
1.1.1 Definition of ionic liquids
Room temperature ionic liquids (RTILs) is a new kind of medium and green
solvent that have been widely reported in various fields[1–3]. It is defined as a liquid
organic salt, which entirely composed of organic cations and organic/inorganic
anions at/ near room temperature. As compared with traditional inorganic salts and
organic solvent, ionic liquids (ILs) have some unique advantages for the iconicity
and liquid properties. For example: 1) Ionic liquids have a wide range of liquid
temperature. 2) Ionic liquids have almost no vapor pressure, which can be used in
high vacuum systems, whilst reducing the environmental pollution caused by
volatilization. 3) Ionic liquids have a good chemical and thermal stability and
excellent oxidation resistance. 4) Ionic liquids have good solubility for a large
number of inorganic/organic substances. 5) Ionic liquids have dual effects of solvent
and catalyst, and can be used as both green solvent and catalyst in the reaction. 6)
Ionic liquids have a high electrochemical stability, high conductivity and a wider
electrochemical window. 7) The properties of the ionic liquid can be easily designed
by the choice of anion and cation thus has a possibility to establish new features
and functions.
In 1914 Walden et al. first reported ethylamine nitrate, a liquid salt at room
temperature (melting point 12 °C)[4]. However, the application of the ethylamine
nitrate is limited, because of the explosiveness of ethylamine nitrate. After many
years studies of ionic liquids by a large number of researchers, ionic liquids have
been widely reported in organic synthesis, catalytic reactions, electrochemistry,
material science, extraction and separation, life sciences, environmental science,
engineering and other fields.[5–9] With the development of ionic liquids, the
definition of ionic liquids is not only limited to liquid at room temperature. The broad
definition of ionic liquids is an organic salt composed of organic cations and
organic/inorganic anions with a melt point below 100 oC.
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1.1.2 Categories of ionic liquid
1.1.2.1 Traditional ionic liquids
There are mainly four kinds of cations in traditional ionic liquids: alkyl-substituted
imidazolium ions [Cnmim]+; alkyl-substituted pyridinium ions [Cnpy]+; alkyl-
substituted quaternary ammonium ions [NRxH4-x]+ and alkyl-substituted quaternary
phosphonium ions [PRxH4-x]+. The structures of these four typical cationic are shown
in Figure 1.1.
Figure 1.1 Typical cations of common ionic liquids
Ionic liquids can be divided into two categories based on the anion. The first-
generation ionic liquids are composed by the halo salt and AlCl3 (or AlBr3, InCl3,
FeCl3), such as [bmim]Cl-AlCl3 etc. But they are extremely sensitivity to water, and
the usage of these ionic liquids should be under a vacuum or inert atmosphere
condition. The drawbacks limited the study and application of the first-generation
ionic liquids. The second generation of ionic liquids developed on the basis of
reported [emim][BF4] ionic liquid with a melting point of 12 °C in 1992.[10] Unlike the
first generation of ionic liquids, the second generation ionic liquids are stable in
water and air. The anions of the second generation ionic liquids mainly include:
[BF4]-, [PF6]-, [CF3SO3]-, [(CF3S2)2N]-, [C3F7COO]-, [C4F9SO3]-, [CF3COO]-,
[(CF3S2)3C]-, [SbF6]-, [AsF6]-, [N2]-, [NO3]-, [HSO4]- etc.
1.1.2.2 Functional ionic liquids
With the development of the ionic liquids, the traditional ionic liquids cannot meet
the needs of research and applications, thus many ionic liquids with special
functional groups on the anion and cation of traditional ionic liquids are well
developed and reported, such as amino groups,[11] carboxylic acid groups,[12]
ester groups,[13] cyano groups,[14] hydroxyl groups,[15] ether groups[16] and thiol
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group.[17] Due to the special functional groups, these functionalized ionic liquid
have been widely used in catalysis, organic synthesis, extraction separation,
preparation of materials and the like. In addition, the physical properties (such as
fluidity, conductivity, liquid range, etc.) and chemical properties (such as polarity,
acidity, coordination ability, solubility, etc.) of functionalized ionic liquids are quite
different from those of conventional ionic liquids. In recent years, several novel
cations have been reported, such as cyclic guanidine ionic liquids, pyrrole ionic
liquids, 1,2,4-Triazole ionic liquids, 1,8-Diazabicyclo [5.4.0] undec-7-ene (DBU) ionic
liquids, protonic ionic liquid, crowned ionic liquids, which exhibited unique properties.
As a special functional ionic liquid, chiral ionic liquids[18] is also widely studied for
both the characteristics of chiral and ionic liquids. They are found more efficient than
traditional chiral solvents in asymmetric synthesis, stereoselective polymerization
and separation of chiral substances.
1.2 Utilization of CO2
In recent years, global warming caused by atmospheric greenhouse gases
(CO2, CH4, N2O, HFCs, PFCs, SF6, etc.) has become one of the most significant
environmental problems. Carbon dioxide (CO2) is the main component of the
greenhouse gases. Since the first industrial revolution, the consumption of fossil
fuels has resulted in a rapid increase of global CO2 emissions. The global CO2
emissions have increased from 2 billion tones to over 36 billion tones since 1900 to
2015. Recent data reported that the increase of fossil CO2 emissions in 2018 is 2.7 %
(range of 1.8 % to 3.7 %) based on the Global Carbon Project. [19]
CO2 is also a very important nontoxic, abundant, natural, inexpensive and
renewable C1 building block. [20–23] Many methods and technologies are
developed for efficient capture, storage and utilization of CO2 such as Carbon
Capture Storage (CCS), Carbon Capture Utilization and Storage (CCUS) and
Carbon Capture Utilization (CCU). The utilization of CO2 as raw materials for
production of energy carriers and chemicals (such as formic acid, urea, methanol,
methane, dimethyl ether, carbonates, carbamates, carboxylic acids, ureas and ring
compounds etc.) is a promising alternative, which can reduce greenhouse gas thus
alleviate the impact of climate change, whilst producing various organic chemical
commodities. Therefore, the development utilization of CO2 has always been a hot
14 | P a g e
topic not only in academic but also international industry.[24–26] With the
intensifying of global warming effect and energy crisis, the using of CO2 as a starting
C1 material has received more and more attentions. Therefore, the efficient
transformation of CO2 into useful organic compounds is of growing interest for
resource utilization and sustainable development.
1.3 Conversion of CO2 to cyclic carbonates
It is well known that CO2 is the highest oxidation state of C and its
thermodynamic properties are stable, which limited the utilization of CO2 as a
starting C1 material. Therefore the CO2 activation always requires high-energy
inputs,[27] such as electrolytic reduction processes, high reaction temperature or
high pressure. Hence, only a small number of chemical pathways for utilization of
CO2 are developed. One of the typical feasible routes is the synthesis of five-
membered cyclic carbonates by cycloaddition of CO2 with epoxides.[28–32] This
cycloaddition reaction is a typical "atomic economy" and "green chemistry" reaction,
and as one of a few successfully industrial products that efficiently utilize CO2 as a
carbon feedstock, cyclic carbonate can be wildly used as excellent solvent in
chemical processes,[33–35] electrolyte components in lithium batteries,[36] useful
monomers for acyclic carbamates[37,38] and carbonates,[39] and intermediates in
the production of fine chemicals, etc. [40,41] There is a large demand of cyclic
carbonates with the developing technology of lithium batteries, carbonates and
dimethyl carbonate, etc. Therefore, the synthesis of cyclic carbonate is a hotspot
that widely studied and has been received more and more attention in recent
decades.
1.3.1 Routes to synthesis cyclic carbonates
There are many routes to synthesis cyclic carbonate, the earliest industrial
production of cyclic carbonate is the phosgene method[42] (Figure 1. 2). The
products can be obtained by reaction of ethylene glycol with phosgene. However,
the phosgene used to produce carbonates is highly toxic, which can cause serious
environmental pollution problems, resulting in the elimination of this old process.
Carothers first reported an ester exchanging method to synthesis cyclic carbonate
catalyzed by metal sodium or sodium methoxide.[43] The synthesis of cyclic
15 | P a g e
carbonate from the cycloaddition reaction of CO2 is quite promising and does not
result in any side products, which has obtained more and more attentions because
that this process can not only produce cyclic carbonates but also reduce
greenhouse gas. And the raw material of CO2 is cheap and easy to get. Compared
with other methods, epoxide is cheap and has high activity, the reaction conditions
of epoxide with CO2, such as temperature, pressure and catalyst are relatively easy.
Therefore, cycloaddition of CO2 with epoxide is the most important and commercial
method.
Figure 1.2 Routes to synthesis cyclic carbonates
1.3.2 Catalysts for synthesis cyclic carbonates
Catalysts are always the most critical issue for a reaction. Many catalyst
systems have been reported for the synthesis of cyclic carbonates by cycloaddition
of CO2 with epoxide. The main industrialization catalysts for the coupling of CO2 and
epoxides are alkali metal salt and quaternary ammonium salts, such as potassium
iodide (KI) and tetrabutylammonium bromide (TBAB). However, the reaction
temperature is always higher than 200 oC with CO2 pressure around 8 MPa,
catalysts need to be separated from cyclic carbonates by decompression distillation.
The harsh conditions led to a high equipment cost and increasing energy
consumption. The design of high activity catalysts has always been a research
hotspot in this field.
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1.3.2.1 Metal containing catalysts
1.3.2.1.1 Metal halides and metal oxide
The metal halide is the earliest reported catalyst for the synthesis of cyclic
carbonates from epoxide and CO2. The metal halide is cheap and with high stability.
However, high temperature and high pressure are often required and results in low
yield of the products. So, some co-catalysts are always needed or used as for the
synthesis of cyclic carbonates. For example, Han et al.[44] reported potassium
halide (KCl, KBr, and KI) in the presence of β-cyclodextrin (β-CD) as a catalyst for
the coupling of CO2 with propylene oxide (PO) to prepare propylene carbonate (PC).
Because of synergetic effect in promoting the reactions, KI-β-CD catalytic system
showed the highest activity among all the catalysts, a 98% yield of PC could be
obtained within 4 hours under the conditions of 120 oC and 6 MPa CO2 pressure.
The catalyst remains high stability after five times recycle. Han et al. also prepared
lecithin[45] and cellulose[46] as a co-catalyst of potassium halides for the
cycloaddition of CO2 with PO to produce PC. Both catalyst systems showed a high
yield and selectivity at 100 °C and 2 MPa conditions. They reported the first
theoretical research about KI and the co-catalytic mechanism of hydroxyl
substances by density functional theory (DFT) method.[47] Werner et al.[48]
prepared a series of amino alcohols combined with KI for the coupling reaction of
CO2 and epoxides. The catalyst system triethanolamine/KI was found to be the
highest yield of cyclic carbonates because of the presence of hydroxyl groups
significantly enhances the catalytic activity. They also reported a polydibenzo-18-
crown-6 as a co-catalyst and polymeric support in combination with KI for the
cycloaddition CO2 and epoxide to cyclic carbonates, which could convert a large
number of terminal epoxides to the desired cyclic carbonates in yields up to 99 %
without any solvent.[49] Furthermore, it could be successfully reused at least 20
times with an excellent yield of 99 %. Shirakawa et al.[50] used KI/tetraethylene
glycol complex for the synthesis of cyclic carbonates from epoxides and CO2. It
showed 99% yield of products within 24 hours at the near room temperature 40 oC
and 1 bar of CO2 without any solvents. Metal halides catalyst system incombination
with a co-catalyst, such as wool powder,[51] organic base,[52–55] formic acid,[56]
N-heterocyclic compounds,[57] lignin,[58] sugarcane bagasse[59] and
17 | P a g e
phosphine[60] have also been extensively studied and exhibited high activity. Metal
oxide catalyst system was wildly studied.[61] For example, Kaneda and co-workers
reported the Mg-Al mixed oxides and used them as efficient catalysts for the
cycloaddition of CO2 with epoxides.[62] Furthermore, the catalysts were found to be
reusable.
1.3.2.1.2 Metal-organic framework
Recently, metal-organic framework (MOF) has been widely reported in trapping
and the conversion of CO2 for its porous structure high specific surface area.[63–68]
Ahn and co-workers[69] reported the utilization of Mg-MOF-74 crystals for
adsorption and conversion of CO2. The adsorption isotherms for CO2 showed 350
mg/g adsorption capacity at 298 K. Then, it was used in cycloaddition of CO2 with
styrene oxide (SO), 95% yields of products could be obtained without any co-
catalysts under reaction conditions of 2.0 MPa and 373 K. Duan group[70] prepared
a discrete singlewalled MOF nanotube based on tetraphenyl-ethylene. Then it was
used in the cycloaddition of CO2 with epoxides and showed a >99% yield of products
within 12 hours under 1 MPa of CO2 and 373 K in the present of tetrabutylammonium
bromide (TBAB). Furthermore, the turnover number (TON) and initial turnover
frequency (TOF) are 17500 and 1000 respectively. Carreon and co-workers[71]
synthesized an amine functionalized zeolitic imidazole framework-8 (ZIF-8) and
used for the producing of chloropropene carbonate (CPC) from CO2 and
epichlorohydrin. ZIF-8 displayed a 100 % conversion of epichlorohydrin high
epoxide conversions because of the high CO2 adsorption capacity of the amine
group. However, the ZIF-8 catalysts lost their distinctive crystalline structure and
catalytic activity during the recycling experiment. Park et al. reported[72] a Ni based
MOF Ni2(BDC)2(DABCO) under solvothermal conditions and used as a
heterogeneous catalyst in the chemical fixation of CO2 to epoxides. The authors
showed the best catalyst had a conversion yield of 93 % after 12 hours reaction
under 80 oC and 2 MPa CO2 with the presence of TBAB as a co-catalyst.
Ni2(BDC)2(DABCO) was reused at least for five times without any obviously loss in
the catalytic activity. Verpoort and co-workers[73] prepared a bimetallic Zn/Co-ZIF
catalyst for conversion of CO2 with epichlorohydrin to CPC. The catalyst showed
93 % yields of CPC within 8 hours under 140 oC and 8 bar of CO2 pressures for
presence of acid and basic sites. Furthermore, the magnetic characteristics of the
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catalyst resulted in the easily separation of catalyst from products by using a magnet,
and the catalyst could be reused for at least eleven cycles.
1.3.2.1.3 Metal porphyrins
Ema et al[74] synthesized a series of bifunctional porphyrin catalysts.
Subsequently, they were found to be excellent catalysts for the coupling reaction of
CO2 with epoxides to produce cyclic carbonates. The magnesium catalyst showed
a turnover frequency (TOF) and turnover number (TON) of 46 000 h-1and 220 000,
and zinc catalyst showed a TOF and TON 40000 h-1 and 310000 because of the
multiple catalytic sites activate the epoxide. In the same year,[75] they also reported
bifunctional MgII porphyrin catalysts with Br−, Cl−, and I− for synthesis of cyclic
carbonates from CO2 and epoxides without any solvent. The best catalyst showed
a TOF and TON 19000 h-1 and 138000 separately caused by cooperative action of
the MgII and Br− and a conformational change of the quaternary ammonium cation.
Furthermore, the mechanism was demonstrated by Density functional theory (DFT)
studies. Ding and co-workers[76] supported a magnesium porphyrin and
phosphonium salt onto porous organic polymer (Mg-por/pho@POP) and used as a
heterogeneous catalyst for conversion of CO2 to cyclic carbonate. This catalyst
showed the highest activity of a heterogeneous catalyst with a TOF up to 15600 h−1.
Jing et al[77] synthesised a series of bisimidazole-functionalized porphyrin cobalt
(III) complexes. They were found good solvent-free homogeneous catalysts for the
production of cyclic carbonates via cycloaddition of CO2 to epoxides and showed
99.0 % yield of CPC under the conditions 120 °C and 2.0 MPa of CO2 for 6 hours.
Furthermore, this catalyst could also be used at 1 bar of CO2.
1.3.2.1.4 Metal (salen) or metal (salphen) complex
Metal complex such as salen, salophen, and related ligands have been widely
reported in the cycloaddition of CO2 with epoxides to form cyclic carbonates as the
easily design and highly tunable structure.[78] Based on the different metal ions,
metal (salen) complex can be classified into Co(salen), Cr(salen), Zn(salen)[79] and
Al(salen) etc. Nguyen and co-workers reported chiral Co(salen) complex with
DMAP as co-catalyst for the coupling of CO2 with epoxides to afford cyclic
carbonate.[80] The conversion of propylene oxide gave good performance of cyclic
carbonate within 1.5 h at 100 oC and 2 MPa CO2 pressure in the presence of CH2Cl2.
Lu and Sun group covalent a series of nucleophilic groups to Cr(salen)
19 | P a g e
complexes.[81] The authors found 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene
(MTBD) functionalized Co(salen) complex was the best catalyst, and could show an
initial TOF 1936 h-1 for the conversion of propylene epoxide (PO) within 1 hour. 97 %
yield of propylene carbonate (PC) could be obtained after 8 hours. The best catalyst
displayed good activity even at room temperature and 0.5 MPa CO2 pressure.
Interestingly, the binary system composed of Cr(salen) complex with MTBD as co-
catalyst was completely inactive at the same conditions. Kleij and co-workers
reported a bunch of Zn(salphen) complexes with TBAI as a co-catalyst for the
cycloaddition of CO2 with epoxides to produce cyclic carbonates.[82,83] Most of the
catalyst systems showed high activity, and the mechanism was also demonstrated
by DFT study. Lu group reported Al(salen) complex combined with TBAB as a co-
catalyst for the coupling of CO2 with epoxide.[84] It showed a catalytic TOF of 3070
h-1. Besides the metal(salen) complex, “Non-Salen” metal complex, such as
transition metal-based complex,[85] and schiff base complex[86,87] were also
widely studied in the cycloaddition reaction of CO2 with epoxide.
1.3.2.2 Organic base catalyst
Organic base is cheap and has diverse structures. It is reported for the fixation
of CO2 with epoxides for its property of absorption and activation of CO2.[88] Such
as organic amine, [89] pyridine,[90] DBU,[53,91] 1,5,7-triazabicyclo[4.4.0]dec-5-ene
(TBD),[92] schiff bases[93] and tetramethyl guanidine (TMG)[94] etc. (Figure 1. 3).
Figure 1.3 Structures of organic base catalysts
However, the activity of organic base catalyst is low, because they can only
20 | P a g e
activate CO2 but not epoxide.[89] The hydrogen bond donor (HBD) is widely used
to activate epoxides by forming the hydrogen bond interaction with epoxides, which
can highly promote the cycloaddition reaction. To improve the catalytic activity of
organic bases, researchers use the synergistic catalytic effect of organic bases and
HBD to form a binary catalytic system for catalyzing the synthesis of cyclic
carbonates from CO2 and epoxides. Reported HBDs include phenol and its
derivatives,[95] boric acid,[96] alkanol amines, cellulose,[97,98] P-cyclodextrin (P-
CD),[99] amino acids[100] and water,[101,102] etc. Shi and co-workers
reported[103] a series of organic bases, such as DMAP, DBU, 1,4-
diazabicyclo[2.2.2]octane (DABCO), triethylamine and pyridine, in combination with
phenol as binary catalyst system to catalyse the cycloaddition reaction. It was found
that the addition of phenol could significantly increase the catalytic activity, and the
DMAP/p-methoxyphenol have been proved to be the most efficient catalyst system,
98 % yield of PC could be achieved under 120 oC and 3.57 MPa of CO2 pressure
after 48 hours reaction. Park et al[100] used a binary catalytic system of naturally
occurring a-amino acids (AAs)/H2O for producing propylene carbonate (PC) from
propylene oxide (PO) and CO2. It was found L-His/H2O system showed highest
yield of PC from coupling of CO2 and PO under CO2 pressure 1.2 MPa and 120 oC
after 3 hours. Roshan et al.[104] studied the effect of water for the organic base
catalyst system. It was found that the addition of water can significantly increase the
catalytic activity of organic bases such as pyridine, imidazole, DMAP, etc. DFT
calculation studies demonstrated that the in situ generated bicarbonate in the water-
CO2-base system were the main active sites, rather than carbamates or hydroxyl
groups.
Zhang group[105] studied the use of binary catalytic system consisting of DBU
and biomass material cellulose. This catalyst system can both activate epoxide and
CO2 by hydrogen interaction of cellulose-epoxide and DBU adsorption of CO2.
Furthermore, DBU can also play the role of a nucleophilic group and promote the
ring opening process of epoxide. The possible catalytic reaction mechanism is
shown in Figure 1.4. The conversion of PO reached 93% within 2 hours at the
optimized reaction conditions of 120 ° C and 2 MPa of CO2. In addition, the catalyst
could be reused with high activity and selectivity.
21 | P a g e
Figure 1.4 The mechanism for the DBU–cellulose catalysed reaction. [105]
1.3.2.3 Ionic liquids catalyst
Ionic liquids catalyst is a kind of organic salt that composed of organic cations
and organic/inorganic anions. In recently, researchers pay more and more
attentions on ionic liquids catalysts for the cycloaddition reaction of CO2 and epoxide
because of its unique properties. Ionic liquids can play the role of both solvent and
catalyst, and the structure can be easily designed and synthesized. To date, a wide
range of ionic liquids catalysts for this reaction have been developed, such as
imidazolium based ILs,[106–109] pyridine based ILs,[12,110] ammonium based
ILs,[111–113] phosphonium based ILs,[105,114–116] organic amines based
ILs,[117–119] metal based ILs,[120–122] supported ILs[68,112,120,123–127]and
poly ILs[128–130] etc.
1.3.2.3.1 Imidazole based ionic liquids
Imidazole based ionic liquid is most reported ionic liquids and have been widely
studied. Deng et al.[131] first reported the use of ionic liquid for catalysing the
cycloaddition reaction of CO2 with epoxide at 2.5 MPa and l10 oC. The catalytic
activity of different ionic liquids was studied. Kawanami et al.[132] investigated the
effect of the side chain length of the imidazolyl ionic liquid on the catalytic activity of
cycloaddition of CO2 with epoxide. The results showed that the longer the carbon
chain had a positive effect on the catalytic effect. The reason might be that the longer
carbon chain will have weaker electrostatic interaction of the anion and cation, and
22 | P a g e
led to the increasing nucleophilicity of the anion. Numerous studies have reported
that the binary catalyst system ionic liquids/metal halides had a high activity.[133]
For example, ZnCl2/[bmim]Br catalyst system reported by Xiao et al.[134] had
excellent activity for the cycloaddition reaction. Promising yield of products could be
obtained under the optimized conditions of 100 oC and 1.5 Mpa of CO2 pressure.
The TOF could reach to 5410 h-1.
Figure 1.5 The mechanism of cycloaddition of CO2 with epoxides by HEMIMB[107]
With the development of ionic liquids, some HBD functionalized ILs are
designed and exhibit excellent catalytic effects than conventional ILs because of the
activation of epoxide by HBD. In recent years, many ionic liquids functionalized with
hydroxyl, carboxyl and amino groups have been widely reported. Zhang et al.[107]
first reported the use of hydroxyl functionalized imidazolium ionic liquids to catalyse
the synthesis of cyclic carbonates by coupling reaction of CO2 and epoxide. The 1-
(2-hydroxyethyl)-3-methylcarbazole bromide (HEMIMB) was found to be the best
catalyst, and 99 % yield and selectivity of PC could be obtained within 1 hour under
the optimized reaction conditions of 125 oC and 2.0 MPa of CO2. The hydrogen bond
interaction between hydroxyl group and epoxide resulted in the polarizing of the C-
O bond and made the ring-open of epoxied easier. The catalytic mechanism was
shown in Figure 1.5. Cokoja et al.[109] synthesized hydroxy-functionalized mono-
and bisimidazolium bromides catalysts for the cycloaddition of CO2 and epoxides.
23 | P a g e
The most active catalyst showed a high conversion at 70 oC and 0.4 MPa CO2).
1.3.2.3.2 Ammonium based ionic liquids
Some of the quaternary ammonium salts have been industrialized. Calo et
al.[135] first discovered that molten quaternary ammonium salts such as TBAB or
TBAI can be used as both solvent and catalyst to catalyse the coupling reaction of
CO2 with styrene oxide (SO) to synthesize cyclic carbonate. 83 % yield of styrene
carbonate (SC) could be obtained under at 120 oC. Lu et al found that the
tetradentate Schiff base aluminum complex (SalenAlCl) and quaternary ammonium
salt could efficiently catalyse the reaction of CO2 with epoxide to prepare cyclic
carbonate. North[136] proposed a new catalytic cycle that fully explains the role of
the tetraalkylammonium bromide co-catalyst.
1.3.2.3.3 Pyridine based ionic liquids
Zhang et al.111 reported a series of carboxyl functionalized ionic liquids as acid-
base bifunctional catalysts for catalysing the reaction. Authors believed that the
enhancement of hydrogen bonding will restrict the activity of anions, thus will
weaken the nucleophilicity and led to the decreasing of catalytic activity.
1.3.2.3.4 Protic ionic liquid
Protic ionic liquid (PILs) that synthesized by acid-base neutralization reaction,
which can provide a proton to form a hydrogen bond with the oxygen atom of the
epoxide, thus being an ideal catalyst for the cycloaddition of CO2 with epoxide to
produce cycli carbonate. He et al.[137] synthesized a series of PILs and used for
this cycloaddition reaction. DBU hydrochloride ([DBUH]C1) was found to be the best
catalyst and showed 97 % yield of PC within 2 hours under 140 oC and 1 MPa CO2.
The catalyst could be recovered by distillation under reduced pressure and reused
at least 6 times without obvious loss of catalytic activity. Tassaing et al.[138]
synthesized a series of TBD based PILs TBDHX and used for this reaction. The
effect of different anions was investigated, TBDHBr was found to be the best catalyst.
Furthermore, DFT calculation was conducted and the results showed that hydrogen
bond interaction between TBDH and PO could reduce the energy of the epoxide
ring-opening process, thereby accelerating the reaction.
1.3.2.3.5 Supported ionic liquid
Homogeneous ionic liquids generally have high catalytic activity. However,
distillation under vacuum conditions is required for the separation and recycling of
24 | P a g e
most homogeneous ionic liquids. This is normally a highly energy-consuming
process. Heterogenization of homogeneous catalysts is an effective method to
facilitate the recycling of the catalyst. Support ionic liquids onto a certain carrier is
an efficient way to heterogenization of homogeneous catalyst, therefor the
separation of supported ionic liquids and the products can be realized by simply
filtration. Takahashi et al.[139] first reported the immobilization of quaternary
phosphonium ionic liquids on silica. The catalytic activity of this catalyst was greatly
improved compared with homogeneous quaternary phosphonium salts due to the
synergistic effect silica and epoxide. Zhang et al.[140] reported a chitosan-
supported ILs to catalyse the cycloaddition reaction of CO2 into epoxide. The
catalyst can activate both epoxide and CO2 by hydroxyl groups in chitosan and
tertiary amines. Furthermore, the catalysts can be recycled five times without loss
of activity. Park et al. grafted a carboxyl functionalized imidazolyl ionic liquid onto
silica gel (CILX-Si) which, and used as a heterogeneous catalyst for the synthesis
of cyclic carbonate from CO2 and epoxide.[141] The synergistic effect of COOH and
halogen anions could promote the catalytic activity, and the catalyst could be
recovered by simple filtration.
Figure 1.6 Mesoporous silic supported ionic liquids[142]
Zhang group[142] synthesized mesoporous silica (mSiO2) based ILs for the
cycloaddition of CO2 with epoxide to cyclic carbonates. The catalyst showed
excellent catalytic because of the larger proportion of mesoporous. XPS analysis
and DFT calculation were conducted to study the good recyclability of this catalyst
(Figure 1.6).
25 | P a g e
1.3.2.3.6 Polymeric ionic liquids
Synthesis of polymeric IL catalysts by polymerization of the double bond is an
interesting topic. The unique advantage of the highly cross-linked polymeric ILs
catalyst made it a high efficient heterogeneous catalyst for the conversion of CO2 to
cyclic carbonate. [129] Han group[143] first reported the use of a highly cross-linked
polymer-supported IL (PSIL). The catalytic activity of the PSIL for the producing of
PC from CO2 and epoxides were investigated. The results showed that nearly all
the PO could be converted to PC within 7 h under 6 MPa CO2 and 383 K. The PSIL
could be easily separated from the products and reused. He and Sakakura[128]
synthesized a poly phosphonium ILs by covalenting bound phosphonium chloride
to the fluorous polymer. The catalyst was conducted as a homogeneous CO2-
soluble catalyst for producing of cyclic carbonates from CO2 and epoxide under
supercritical CO2 conditions. 95 % yield of PC was obtained at 150 oC and 8 MPa
after 8 hours reaction. The catalyst could be recovered by filtration. High activity and
selectivity were achieved after reused 7 times.
Figure 1.7 Synthesis of PILs in this study. [144]
Zhang et.al[144] prepared a series of hydroxyl-functionalized poly(ionic liquids)
(PILs) and used for the synthesis of cyclic carbonates via cycloaddition of CO2 and
epoxides (Figure 1.7). Because of synergetic effect on promoting the reaction by the
hydroxyl and bromide anion, the best PILs displayed a 99% yield and 100%
selectivity of PC within 4 hours under 130 oC and 2.5 MPa of CO2 pressure with a
26 | P a g e
catalyst loading of 1.0 mol%.
Figure 1.8 Structure of DFP[145]
Zhang group[145] also reported a dicyandiamide–formaldehyde polymer (DFP)
based polyquaternium ILs and employed for cycloaddition of CO2 with epoxides
(Figure 1.8). Structure was shown in Figure 1.8. The authors found that the
ammonium bromide modified polyquaternium ILs (ABMDFP) was the optimal
catalyst, and 99 % yield and 99 %selectivity of PC could be obtained within 3.5 hour
under the optimal reaction conditions of 130 °C and 2.0 MPa of CO2 with a catalyst
loading of 2.0 mol%. The catalyst could be easily recovered by filtration and reused
six times with only a slight loss of catalytic activity.
Figure 1.9 General route for the synthesis of carboxyl functionalized phosphonium-based
PIL[146]
27 | P a g e
In year of 2017, Zhang group[146] synthesized phosphonium-based polymeric
ionic liquids (PILs) by microfluidic technique (Figure 1.9). The average diameter
sizes of the particles could be turned from 6.4 to 375 nm. They are successfully
conducted in the cycloaddition of CO2 with epoxides to form cyclic carbonate. The
best catalyst displayed 99 % yield of PC after 4 hours at 150 oC and 2 MPa of CO2.
Authors demonstrated that carboxylic acid group could activate the ring-opening of
epoxide by in situ FTIR.
1.3.3 Cycloaddition of CO2 and epoxide under mild conditions
Although most of the catalyst systems show a good yield to produce carbonates,
high temperatures (>100 °C) and/or high CO2 pressures, are always needed. Such
reaction conditions not only increase energy consumption and require specific
equipment, but also raise certain operational risks. Hence, great efforts have been
focused on the development of efficient and sustainable catalyst systems that can
be carried out chemically converting CO2 at relatively mild reaction conditions. In
this respect, many catalysts have been synthesized and exhibited good
performance in the synthesis of cyclic carbonates from CO2. For example,
metal−based catalysts, such as metal(salen), MOF, metal porphyrin were reported
to have a good yield of cyclic carbonates at atmospheric pressure and/or room
temperature because of its multi-activity sites consisting of metal ions and halide
ions. In this respect, North group made great contributions. North and co-workers
reported an Cr(III) salphen complexes for the cycloaddition reaction under ambient
conditions with the presence of TBAB (tetrabutylammonium bromide).[147] The
catalyst system could catalyse the cycloaddition of CO2 to various terminal epoxides
under ambient conditions. It was found that both the catalyst and co-catalyst played
an important role in this reaction via interacting with epoxide to form an intermediate
complex. In the same year, North et al. reported[147] a chromium-based complex
functionalized with amino groups. The amino-functionalized Cr(III)(salen) complex
showed similar results with Cr(III)(salophen) complexes. The group of He
reported[148] a bunch of bifunctional Zn(salen) complexes composed by multiple
HBD and ammonium bromides groups for coupling of CO2 with styrene oxide to
produce 4-phenyl-1,3-dioxolan-2-one. Due to the synergistic effects of HBD on
epoxide activation, the best catalyst could show 90 % yield of product within 12
28 | P a g e
hours under 120 oC and 0.1 MPa CO2 without any co-catalysts. However, these
catalysts need the aid of DMF as a solvent. Ma et al.[149] reported a nbo MOF
composed by Lewis active sites and metal Cu for this coupling of CO2. MMCF-2
[Cu2(Cu-tactmb)(H2O)3(NO3)2] was found to be the best catalyst, and 95.4 % yield
of PC could be obtained after 48 hours reaction under room temperature and 1 atm
CO2 with the presence of Bu4NBr as a co-catalyst. Jiang et al.[150] reported the
integration of photothermal effect of carbon-based Zn-MIF materials for the
cycloaddition of CO2 with epoxide. The best catalyst showed 94 % yield of cyclic
carbonate after 10 hours with the presence of TBAB as co-catalyst and DMF as
solvent under 1 bar CO2, 300 mW·cm-2 full-spectrum irradiation and ambient
temperature. Furthermore, catalytic activity of this catalyst system would decrease
sharply to < 5 % and 14 % without co-catalyst or light irradiation respectively.
Authors also studied conversion of a mixture gas (0.15 bar CO2, 0.85 bar N2) at the
same conditions. This catalyst system displayed 90 % yield of cyclic carbonate when
the reaction time was extended to 30 hours. This work is the first report on
integration of photothermal effect for the cycloaddition of CO2 with epoxide to
produce cyclic carbonate. Other metal based catalysts system, such as dual-walled
cage MOF,[151] diphenylporphyrin]manganese(III) chloride (DPP-
MnCl)/phenyltrimethylammonium tribromide (PTAT),[152] metal porphyrin based
porous organic polymer (POP-TPP)/TBAB,[153] bisimidazole-functionalized
porphyrin cobalt(III) complexes[154] were also reported for the cycloaddition of CO2
to produce cyclic carbonate under mild conditions, and showed promising catalytic
activities.
Binary catalyst systems, such as organic base/HBD and organic base/ metal
halides were widely reported due to the activation of epoxides by a nucleophile and
a strong hydrogen bond or activation of CO2. Hirose and co-workers[155] reported
the use of pyridine methanol as HBD associated with TBAI as a binary system for
the cycloaddition reaction of epoxide and CO2 to produce cyclic carbonates. A series
of HBD was studied, and 2-pyridinemethanol was found to be the best HBD with
TBAI, showed 92 % yield of CPC within 24 hours under room temperature (25 oC)
and 1 bar CO2 (balloon). Interestingly, optically pure epoxides could be forming the
corresponding products with minimal loss in the ee values. Wang and co-workers[96]
investigated a series of boronic acids as HBD combined with TBAI for the coupling
29 | P a g e
of CO2 with epoxides into produce cyclic carbonates in different solvents under mild
conditions. In this study, H2O was found to be the optimal solvent. The best boronic
acide/TBAI system could show 90 % yield and 90 % selectivity of corresponding
cyclic carbonate within 4 hours under 50 oC and 1 MPa CO2 in H2O. Moreover, the
products would automatically separate from the mixture reaction system after the
reaction. Authors investigated the recycling experiment by using a polystyrene
supported boronic acid. The result showed that the boronic acid could be used at
least 8 times without any obvious loss of catalytic activity. Hirose et al.[88] also
studied the use of a serious organic base combined with TBAC as a binary system
for the coupling of CO2 with epoxide to produce cyclic carbonates. A bunch of
organic bases was studied, such as DBU, DMAP, pyridine etc. DBU/TBAC was
found to be the best catalyst system and showed 96 % yield of cyclohexene oxide
within 20 hours under 120 oC and 1atm CO2. The binary system of benzyl bromide
combined with organic base catalyst system was also reported by Hirose group, and
showed high activity at mild conditions of 25 -65 oC and 1 atm CO2.[156] Recently,
Werner et al.[157] reported a CaI/crown ethers catalyst system for the synthesis of
internal and trisubstituted cyclic carbonates from bio-derived epoxides and CO2. The
best catalyst can catalytic various internal epoxides to the respective carbonate with
isolated yields up to 98 % within 24 hours at only 45 °C, 0.5 MPa CO2 pressure with
a catalyst loading of 5 mol. Binary systems, such as MgBr/Phosphine,[60]
DBU/CaBr,[53] DBU/ascorbic acid[91] etc. were also reported for the coupling of
CO2 to produce cyclic carbonate under mild conditions, and showed promising
catalytic activities.
Recently, most studies have focused on organocatalyst, especially ionic
liquids.[30,158–161] Dyson and co-workers[162] studied the roles of the ring protons
of imidazolium salts in the cycloaddition of CO2 with epoxides to produce cyclic
carbonate catalysed by imidazolium and related salts. The results demonstrated that,
the nucleophilicity of the anion played the key role in the overall activity, as
stabilization of intermediates by C2, C4, or C5 protons in imidazolium salts took
place. Therefore, the reactivity of the halide anion strongly depends on the nature
of the cation and cosolvents. Wang and co-workers[163] reported a dual hydroxyl
functional mesoporous poly(ionic liquid)s as recyclable heterogeneous catalysts for
the cycloaddition of epoxides with CO2 under mild conditions. The best catalyst
30 | P a g e
showed 99.4 % yield of CPC at 0.1 MPa CO2 and 70 oC after 48 hours reaction.
Furthermore, it could be easily recovered and reused with stable activity. Ma et
al.[164] reported that the use of porous ionic polymer as heterogeneous for capture
of CO2 and catalyse CO2 to form cyclic carbonate. The polymer could chemically
fixation CO2 with epoxide to cyclic carbonate under mild conditions due to the porous
nanostructure and large surface area. The catalytic activity was even higher than its
corresponding homogeneous quaternary salt catalyst. Similarly, mesoporous-
macroporous layered poly ionic liquids with an adjustable pore structure and highly
dense catalytic active site was reported by Wang and Zhou et al.[165] to catalyse
the conversion of CO2 to cyclic carbonate under 0.1 MPa CO2 and mild temperature.
The catalyst exhibited a high yield (>99%) and allowed recycling of the IL solvent.
Most recently studies have been focused on protic ionic liquids (PILs), which
exhibited not only excellent ability of reversible CO2 capture but also highly efficient
CO2 chemical conversion even under ambient conditions since the powerful H-
bonding.[166–168] Han et al[169] employed a novel dual-ionic liquid system for
cycloaddition of epoxides with CO2 under temperature from 30 to 60 °C at 1 atm,
the results showed 95 % yield of CPC could be obtained after 20 hours at 30 oC and
1 atm CO2 without any solvents. Zhang et al.[170] synthesized a bunch of protic
ionic liquids for the conversion of CO2 with styrene oxide (SO) to Styrene Carbonate
(SC) at mild conditions. They found 4-(dimethylamino) pyridine hydrobromide
([DMAPH]Br) showed highest catalytic activity, 96 % yield of SC could be obtained
after 4 hours with a catalyst loading of 1 % under 120 oC and 1 atm. Furthermore,
authors studied the conversion of flue gas (mixture of 15% CO2 and 85% N2) with
SC. The best catalyst displayed 92 % yield within 14 hours under the same reaction
conditions. Shirakawa et al.[171] reported the use of a protic triethylamine
hydroiodide as an effective one-component catalyst for the coupling of CO2 with
epoxide at 40 °C under ambient pressure. However, the catalytic activity decreased
obviously during the recycling experiment because the partial loss of the catalyst for
the sublimation property under the distillation conditions. PILs such as pyrazolium
based PILs,[172] imidazole and pyridine based PILs[173] were also reported for the
coupling of CO2 with epoxide to form cyclic carbonate under mild conditions, and
they all showed excellent catalytic activities at this mild conditions.
31 | P a g e
1.4 Research contents
Although some of the catalyst systems show a good yield to produce
carbonates, even at mild conditions, unsatisfactory activities of large catalyst loading
and long reaction time (>24h) compared to high temperature and pressure, the
presence of metals and/or toxic solvents are still drawbacks that need to overcome.
Therefore, the design of efficient, green and metal-free catalysts is still a great
challenge toward effective CO2 conversion under mild conditions. For energy
efficient reasons, we designed a series of functional ILs and used them for
catalysing the cycloaddition reaction of CO2 with epoxides under mild conditions.
The major work and results for this dissertation are summarized as follows:
1 A series of carboxylic acid-based functional ionic liquids (CABFILs) were
facilely prepared by a one-step synthesis method. They displayed reversible
temperature-controlled phase transitions in PC, which were useful for the coupling
reaction and separation processes. CABFILs were successfully used in
reaction−separation for conversion of CO2 to carbonates under metal-free and
solvent-free conditions. Besides, IL 3a displayed high activity, and nearly 92% PC
yield was obtained within 20 min and could be readily separated by filtration at room
temperature for easy recycling. This approach helps to avoid further waste of the
subsequent separation step, as well as a highly effective way to combine the
benefits of heterogeneous and homogeneous catalysts, which is of great interest
from the viewpoint of energy savings and chemical engineering.
2. An efficient 1,8-diazabicyclo- [5.4.0] undec-7-ene (DBU) based bifunctional
protic ionic liquids (DBPILs) was easily prepared by acid-base reaction at room
temperature. DBPILs that composed by alkoxy anion, protic acid and nucleophilic
groups exhibited high activity for the coupling reaction of CO2 and epoxide under
mild conditions. As a metal free catalyst, the best DBPILs showed a 92 % yield of
products within 6 hours at 30 oC and 1bar CO2 without any solvents and co-catalysts.
And it could afford carbonates in good yields with broad epoxide substrate scope
and CO2 from simulated flue gas (15% CO2/85% N2).
3. DBU based ionic liquids containing aluminium (DILA) catalyst was
synthesized based on dissociating feature of proton from DBPILs. DILA was used
as a single-component and solvent-free catalyst for the conversion of CO2 to cyclic
carbonates with epoxide at mild conditions. DILA showed a catalytic activity of 96%
32 | P a g e
within 6 h in catalysing the reactions of CO2 with epoxides at 30 oC and 1 bar CO2,
because of the efficiently activating epoxides. The effect parameters such as
temperature, reaction time and catalyst dose were investigated.
4. A series of cross-linked poly (ILs) membranes (CPILM) were prepared and
used as highly efficient heterogeneous catalysts for fixation of CO2 with epoxide at
mild conditions. CPILM could show comparable activities in the coupling of epoxide
and CO2 with the traditional homogenous catalysts, because of the activity of CO2
and “homogenous-surroundings” caused by swellable properties. Swelling
behaviour was studied and found to be consistent with the experimental results of
the catalytic activity. The dependence of conversion yield on catalyst dose, reaction
temperature and time were investigated. The best CPILM could show a 90% yield
of carbonate within 24 hours at 50oC and 1 bar of CO2.
5. A series of metalloporphyrin ionic liquids (MPILs) that combine the
advantages of ionic liquid and porphyrin were designed and synthesized by one step
method. The structure and surface appearance of these BPILs were investigated.
These BPILs catalysts have multiple active sites and a good capacity of visible light
absorption due to the advantages of functional ionic liquids and metal porphyrin part,
thus can greatly reduce the energy inputs by using the visible light. They were
successfully used as a photocatalyst in cycloaddition reaction of CO2 with epoxide
to produce carbonate at 1 bar pressure under irradiation of a visible light.
33 | P a g e
Chapter 2: Temperature-Controlled Reaction-Separation
for Conversion of CO2 to Carbonates with Functional
Ionic Liquids Catalyst
2.1 Introduction
The combination of activity and recovery of homogeneous catalysts is
recognized as a great challenge in catalysis research from an industrial point of
view.[174] The reported homogeneous catalysts are usually more efficient, while it
is costly to reclaim them from reaction products. By contrast, heterogeneous
catalysts can be easily separated from the products and reused. But they are
inefficient, on the same time, the high temperatures and pressures are often
demanded, which make them practically excess costs. This has promoted the
development of efficient strategies for homogeneous catalysis and heterogeneous
separation.[175,176] Recently, Wang et al. [177] has reported the interesting finding
- the reversible liquid–liquid phase transition of IL-H2O systems by
bubbling/removing CO2. These unique IL-H2O systems are successfully used for
facile one-step synthesis of Au porous films. The group of Xiong[178] has prepared
IL-based cross-linked polymeric nanogels (CLPNs) and find that they display
reversible, temperature-driven nanoge-macrogel transitions in methanol. The
reversible phase transition phenomenon supplied a novel strategy for the efficient
combining of activity and recovery of homogeneous catalysts.
The efficient utilization of carbon dioxide (CO2) also remains the important issue,
as these may reduce the greenhouse gas and produce various organic chemical
commodities. [179–182] One of the typical viable routes is the synthesis of five-
membered cyclic carbonates via the cycloaddition of CO2 with epoxides.[183–185]
Cyclic carbonates can be extensively used as polar aprotic solvents, raw materials,
and intermediates in the synthesis of pharmaceuticals and fine chemicals,[186–188]
which made this process very attractive and important.
To this end, various catalysts have been developed.[189–194] Ionic liquids (ILs)
have been demonstrated efficient homogeneous catalysts for the synthesis of cyclic
carbonates.[132] Many functional ILs containing a Lewis acid and a nucleophile
34 | P a g e
have been reported. Cokoja group[195] synthesized hydroxy-functionalized mono-
and bisimidazolium bromides catalysts for the cycloaddition of CO2 and epoxides.
The most active catalyst showed a high conversion at very mild reaction conditions
(70 oC, 0.4 MPa CO2). Han et al.[196] prepared carboxylic acid groups-
functionalized ammonium salts for the fixation of CO2. North[197] proposed a new
catalytic cycle that fully explains the role of the tetraalkylammonium bromide co-
catalyst. Park et al.[141] exploited carboxyl-group-functionalized imidazolium-based
ionic liquids (CILs) and grafted onto silica gel for cycloaddition of CO2. Zhang et
al.[198] provide a boronic acids/onium salts system as efficient organocatalysts for
the conversion of CO2 with epoxides in H2O under mild conditions. We also reported
four kinds of carboxylic acid–base bifunctional catalysts (ABBCs) for the reaction of
epoxides with CO2.[199] Although, the reported homogeneous systems provide
higher activity, it is often inconvenient for separation. Based on the problems in
homogeneous catalytic processes, some heterogeneous catalysts have been
developed for the CO2 chemical conversion. In contrast, heterogeneous systems
are easier to separate, but they are inefficient (The most efficient metal-free
heterogeneous catalysts turnover frequencies (TOFs) are 90 h−1)[200] and hard
reaction conditions are always needed. Hence, it is highly necessary to explore a
convenient approach to realize both high activity and quick separation of catalysts.
Figure 2.1 Photograph showing the temperature-controlled phase transitions in PC (3a =
8 wt % and PC = 92 wt %).
Taking account of these issues, we exploited a series of carboxylic acid–based
functional ILs (CABFILs) as single-component, metal-free homogeneous catalysts
for cycloaddition of CO2 with epoxides into cyclic carbonates. Interestingly, this type
35 | P a g e
of ILs displayed temperature-dependent phase transitions in propylene carbonate
(PC) by controlling the chain length of carboxyl group. Thus, these catalysts offered
an efficient way to recover the homogeneous catalysts. When the catalysts were
added into PC, such a liquid/solid phase remained separated at room temperature
(Figure 2.1 step a). When heated, they readily dissolved in PC (Figure 2.1 step b),
where they could react effectively. As the mixture got cooled, the solubility of
CABFILs in PC dramatically decreased. On the same time, the catalysts precipitated
spontaneously, and the phases were separated again (Figure 2.1). So, we could
simply filtrate to recover the catalysts precipitated from the products. Besides, the
optimal ILs displayed high productivity and stability because of the activation of
epoxide and CO2. Nearly 92% PC yield and 99% PC selectivity were obtained within
20 min under metal-free and solvent-free conditions (TOFs=276 h−1). Such a
temperature-dependent dissolution-precipitation transitions behaviour helped to
avoid further waste of the subsequent separation step, which could be used to
realize the coupling of reaction and separation in energy saving and industrial
application.
2.2 General information
Carbon dioxide was supplied by Beijing Analytical Instrument Factory with a
purity of 99.95%. 1,2-Epoxyoctane, Styrene oxide and cyclohexene oxide were
purchased from Alfa Aesar-A Johnson Matthey Company, (R)-2-Oxiranylanisole, 4-
Dimethylaminopyridine, Bromoacetic acid, 3-Bromopropionic acid and 4-
Bromobutyric acid were bought from Aladdin Reagent Co. Other reagents and
chemicals (analytic grade) were bought from Sinopharm Chemical Reagent Co., Ltd,
and were used without further purification. GC-MS were measured on a Finnigan
HP G1800 A. GC analyses were performed on an Agilent GC-6890 equipped with
a capillary column (DB-624, 30 m×0.32 μm) using a flame ionization detector. NMR
spectra were recorded on a Bruker 300 or Varian 400 spectrometer. All calculations
were carried out by the use of the B3PW91 functional with the 6-311++G (d,p) basis
set as implemented in the Gaussian 09 program package.
36 | P a g e
2.3 Experimental section
2.3.1 Main equipments
Gas chromatography- mass spectrometry (GC-MS): Agilent 6890N/5975B GC-
MS,
Gas chromatograph (GC): Agilent 6820 GC
Fourier transform infrared spectrometer (FT-IR): Thermo Nicolet 380
Nuclear magnetic resonance instrument:ARX400 Bruker, Switzerland
Thermogravimetric analyzer:Thermogravimetric Analyzer 2050
2.3.2 Synthesis of catalysts
Scheme 2.1 One step synthesis of catalysts in this study.
All the catalysts were synthesized by using one-step method. In a typical
reaction, 4-dimethylaminopyridine (50.00 mmol) and BrCnH2nCOOH (60.00 mmol)
were poured in sequence into a 250 mL three-necked flask and dissolved in ethyl
acetate. The mixture was stirred for 12 h at 50oC until the solid product was not
increased. After the reaction, the top phase was immediately poured out and the
residue was washed three times with ethyl acetate and then dried at 50oC for 12 h
under vacuum. The structures of these ILs were confirmed by NMR and IR
spectroscopy, no impurities were found by NMR.
2.3.3 Characterization of the catalysts
The catalysts were characterized by thermogravimetric analysis (TGA,
PERKIN-ELMER7 Series Thermal Analysis System) at a heating rate of 10oC min-
1. The morphology of the ILs was observed using a scanning electron microscope
37 | P a g e
(JEOL JSM 6700F). Fourier transform infrared (FT-IR) spectra were recorded on a
Thermo Nicolet 380 spectrophotometer with anhydrous KBr as standard (Thermo
Electron Co.). NMR spectra were recorded on a Bruker 300 or Varian 400
spectrometer in DMSO-d6. The characterizations are shown as following:
[CEDMAPy]Br (1a): Viscous solid; 1H NMR (DMSO-d6): δ 13.28 (s, 1H), 8.26
(m, 4H), 6.9 (m, 4H), 4.31 – 4.24 (m, 2H), 3.24 – 3.14 (m, 6H); 13C NMR (DMSO-
d6): δ 170.69, 157.38, 143.46, 139.49, 107.45, 39.6, 26.83.
[CPrDMAPy]Br (2a): Solid; 1H NMR (DMSO-d6): δ 12.88 (s, 1H), 8.27 (m, 4H),
6.9 (m, 4H), 4.37 (m, 2H), 3.2 – 3.15 (m, 6H), 2.90 (m, 2H); 13C NMR (DMSO-d6): δ
170.65, 156.75, 142.28, 140.17, 107.33, 52.94, 39.59, 34.26.
[CBDMAPy]Br (3a): Solid; 1H NMR (DMSO-d6): δ 13.25 (s, 1H), 8.32 (dd, J =
91.5, 6.8 Hz, 4H), 7.07 (dd, J = 82.3, 7.2 Hz, 4H), 3.35 (m, 2H), 3.20 (s, 6H), 2.57
(d, J = 67.0 Hz, 2H), 1.04 (d, J = 229.5 Hz, 2H); 13C NMR (DMSO-d6): δ 170.05,
157.43, 139.57, 107.44, 40.01, 39.59.
[CPeDMAPy]Br (4a): Solid; 1H NMR (DMSO-d6): δ 13.28 (s, 1H), 8.38 (ddd, J
= 11.3, 7.6, 2.6 Hz, 4H), 7.08 (m, 4H), 3.36 (s, 2H), 3.19 (s, 6H); 13C NMR (DMSO-
d6): δ 175.15, 157.43, 139.50, 107.46, 33.40, 30.23, 21.38.
Figure 2.2 The FT-IR spectra of 1a-4a
4000 3000 2000 1000 0
Wavenumber (cm-1)
1734[CEDMAPy]Br (1a)
[CPrDMAPy]Br (2a)
[CBDMAPy]Br (3a)
[CPeDMAPy]Br (4a)
13862930
38 | P a g e
2.3.4 1H NMR and 13C NMR of Products
4-methyl-1, 3-dioxolan-2-one (6a):
1H NMR (CDCl3, TMS, 400 MHz): 1.49 (d, J = 6.0 Hz, 3H); 4.05 (t, J = 8.8 Hz,
1H); 4.60 (t, J = 8.0 Hz, 1H); 4.86–4.94 (m, 1H); 13C NMR (CDCl3, TMS, 100.4 MHz):
18.95, 70.46, 73.51, 154.95 (C=O)
4-hexyl-1,3-dioxolan-2-one (6b):
1H NMR (CDCl3, TMS, 400 MHz): 0.84 (t, J = 13.1 Hz, 3H); 1.24–1.28 (m, 7H);
1.34 (t, J = 9.6 Hz, 1H); 1.65 (t, J = 11.7 Hz, 2H); 4.08 (t, J = 15.8 Hz, 1H); 4.53 (t,
J = 15.8 Hz, 1H); 4.74 (t, J = 6.9 Hz, 1H); 13CNMR (CDCl3, TMS, 100 MHz): 14.29,
22.52, 24.45, 28.87, 31.63, 33.44, 69.69, 77.49, 155.35 (C=O).
4-chloromethyl-1, 3-dioxolan-2-one (6c):
1H NMR (CDCl3, TMS, 400 MHz): 1.490 (d, 2H, J = 6.0 Hz); 4.05 (t, 1H, J = 8.4
Hz); 4.60 (t, 1H, J = 8.0 Hz); 4.86–4.94 (m, 1H); 13C NMR (CDCl3, TMS, 100.4 MHz):
18.95, 70.46, 73.51, 154.95 (C=O).
4-phenyl-1, 3-dioxolan-2-one (6d):
O O
O
O O
O
C6H13
39 | P a g e
1H NMR (CDCl3, TMS, 400 MHz): 4.34 (t, 1H, J = 8.4 Hz); 4.80 (t, 1H, J = 8.4
Hz); 5.68 (t, 1H, J = 8.0 Hz); 7.35–7.44 (m, 5H); 13C NMR (CDCl3, TMS, 100.4 MHz):
71.10, 77.92, 125.81, 129.12, 129.63, 135.70, 154.81 (C=O).
4-phenyloxymethyl-1, 3-dioxolan-2-one (6e):
1H NMR (CDCl3, TMS, 400 MHz): 4.15 [dd, 3J = 4.4 Hz, 2J = 10.8 Hz, 1H,
OCH2], 4.24 [dd, 3J = 3.6 Hz, 2J = 10.8 Hz, 1H, OCH2], 4.55 [dd, 3J = 8.4 Hz, 2J =
6 Hz, 1H, PhOCH2], 4.62 [t, 3J = 8.4 Hz, 1H, PhOCH2], 5.03 [m, 1H, OCH], 6.91 [d,
3J = 8.0 Hz, 2H, C6H5], 7.02 [t, 3J = 7.4 Hz, 2H, C6H5], 7.31 [t, 3J = 8.0 Hz, 2H,
C6H5]. 13C NMR (CDCl3, TMS, 100.4 MHz): 66.17, 68.84, 74.11, 114.57, 121.92,
129.62, 154.65(C=O), 157.71.
2.3.5 Procedure of the cycloaddition reaction of CO2 with
propylene oxide
The coupling reaction of carbon dioxide and epoxide was carried out in a 25 mL
stainless-steel reactor equipped with a magnetic stirrer and an automatic
temperature control system. In a typical reaction, appropriate amounts of PO and
catalyst were charged into the reactor at room temperature, Then, CO2 was added
to a suitable pressure from a reservoir tank to maintain a constant pressure. Control
the temperature within the desired range afterwards. After the reaction, the reactor
was cooled to room temperature in a water bath and remaining CO2 was vented out
slowly. The organic products were separated from the catalyst by filtration and
analysed by GC-MS and GC. Agilent 6890/5973 GC-MS was equipped with a FID
detector and a DB-wax column. The catalyst was washed with ethyl acetate three
times and dried under vacuum for the recycling experiment.
O O
O
40 | P a g e
2.3.6 Reaction equipment
Figure 2.3 Reaction equipment. 1. CO2 cylinder,2. Filter,3. Thermocouple,4.
Transformer,5. Reactor,6. Magnet,7. Blender, 8 Heater
2.4 Results and discussion
Figure 2.4 Structure and photographs of CABBILs (1a-4a)
A series of these CABFILs (Figure 2.4) were obtained through one-step
synthesis process at room temperature. Their solubility in PC at 25 oC was showed
in Figure 2.5. It could be observed that the carboxylic chain length of CABFILs had
great influence on solubility of CABFILs in PC: the solubility decreased sharply from
14.8% to 0.4% with the increase of chain length from 2 to 5 (1a-4a) at room
temperature. The possible reason for the different solubility was mainly attributed to
the effects of the different nonpolarity of CABFILs.[201]
41 | P a g e
Figure 2.5. The solubility of IL (1a-4a) in PC at 25oC (Determined by 1H NMR, see Fig
S11-S14).
Figure 2.6. The solubility of IL 3a in PC at different temperatures (Determined by
gravimetric method).
Then, 3a was used as a representative example to investigate the temperature-
0
2
4
6
8
10
12
14
16
4a3a
2a
So
lub
ilit
y (
g/1
00m
l)
Catalyst
1a
20 40 60 800
4
8
12
So
lub
ilit
y (
g/1
00
ml)
Temperature (o
C)
42 | P a g e
dependent solubility. The solubility of 3a in PC was as low as 0.27% at 10 oC and
increased obviously as the temperature went up (Figure 2.6). Hence, when 3a (8
wt%) was added into PC, such a liquid/solid mixture remained separated at room
temperature. When temperature went up, 3a readily dissolved in PC. As the mixture
was cooled to room temperature, the catalysts precipitated spontaneously, and the
phases separated again. We reasoned that the temperature-dependent solubility of
CABFILs in PC was mainly attributed to the intermolecular hydrogen bonding of the
ILs components.[202]
Then, nuclear magnetic resonance (NMR) studies were performed in order to
gain insight into the mechanism. First, tetraglyme was selected as a destroyer,
which could compete in the formation of hydrogen-bond,[203] to investigate the
intermolecular hydrogen bonding of the ILs components on the effect of the solubility.
The 1H NMR spectra of 3a with and without tetraglyme was shown in Figure 2.7,
the signal at 14.47 ppm was associated with the carboxylic proton, the signal of
carboxylic proton decreased after mixed with tetraglyme. Such a trend suggests
weakened interaction energy.[204] This was mainly because the hydrogen-bond of
O-H···O between carboxylic protons was broken. Similar result was found in C2 /C6
proton of pyridine ring, which indicated the broken of the hydrogen-bond C-H···Br-.
Figure 2.7. The 1H NMR spectrum of IL 3a with and without tetraglyme.
14 12 10 8 6 4 2
δ/ppm
C2/C6-COOH
CDCl3
3a
3a + Tetraglyme
14.47
14.10
43 | P a g e
Figure 2.8. The temperature-dependent 1H NMR spectrum of IL 3a in [D6] DMSO
Temperature-dependent NMR was shown in Figure 2.8 to provide further
evidence for the effect of the temperature on the solubility of ILs in PC. The signal
of carboxylic proton and C2 /C6 proton of pyridine ring also decreased when the
temperature increased from 30 oC to 80 oC, which may be caused by the broken of
the hydrogen-bonds O-H···O and C-H···Br-.[205]
Figure 2.9. (a) Molecular structure of 3a and the intermolecular hydrogen bonding of the
ILs components. See the APPENDICES for computational details.
44 | P a g e
The DFT calculations were shown in Figure 2.9 for further study of the
intermolecular hydrogen bonding. All calculations were carried out by the use of the
DFT functional with the 6-311++G (d, p) basis set as implemented in the Gaussian
09 program package. The result indicated that moleculars of 3a showed a tendency
to form a class of clusters with self-aggregation through hydrogen bonding network.
Of all the clusters, tetramolecular clusters was relatively more stable, and the
structure of the tetramolecular clusters was shown in Figure 2.9 (a). Four carboxyl
groups were forming tetramers that were connected by strong hydrogen bonds (O-
H···O distance of 1.572-1.656Å). Besides several C-H···Br contacts between Br-
anions and the cations can be observed, ranging from 2.36 to 2.87 Å. The hydrogen
bonds of C-H···Br led to the four moleculars aggregation and formed a
tetramolecular cluster.
Figure 2.10 Hydrogen bonding interaction between 3a and PC. See the APPENDICES for
computational details.
Strong hydrogen bonds were also found between 3a and PC with an O-H···O
distance of 1.93-1.94 Å and a C-H···O distance of 2.40-2.74 Å, respectively [Figure
2.10]. Therefore, based on the above results, a possible mechanism of reversible
temperature-dependent phase transitions behaviour of CABFILs was proposed.
The nonpolarity of CABFILs with a longer carboxylic chain was higher than those
with a shorter chain, as well as a stronger intermolecular hydrogen bonding, which
made them hardly dissolved in polar solvent PC at room temperature. When heated,
the intermolecular hydrogen-bond network of O-H···O and C-H···Br was broken.
Then, the molecular of ILs diffused into PC. Finally, the formation of hydrogen bond
between CABFILs and PC led to the dissolution of CABFILs. The dissolution
45 | P a g e
process ended as precipitation-dissolution reached equilibrium.
Figure 2.11 SEM images of the ILs 3a.
SEM images of the ILs 3a were also shown in Figure 1, and the surface profile
of 3a was like the brain wrinkle (Figure 2.11) due to the tetramolecular cluster
structure caused by the hydrogen bonding network. This particular shape could
provide increased surface area and was useful in catalytic processes.
Table 2.1. Catalysts screening for the synthesis of propylene carbonatea
Entry Catalysts PO Conv. (%)b PC Select. (%)b
1 [BPy]Br 47 99
2 [CEDMAPy]Br (1a) 89 99
3 [CPrDMAPy]Br (2a) 94 99
4 [CBDMAPy]Br (3a) 90 99
5 [CPeDMAPy]Br (4a) 89 99
6 c [CBDMAPy]Br (3a) 99 99
7 c [{(CH2)3CO2H}inic]Br111 73 96
8 c [{(CH2)3CO2H}bpy]Br111 83 99
9 [CBDMAPy]Br (3a) 99 99
10 Poly imidazolium salt 90 99
aReaction conditions: PO (14.3 mmol), catalyst (1.0 mol%), CO2 pressure (2.0 MPa), reaction
time (1.0 h) and temperature (120 oC). bConversion and selectivity were determined by GC using
biphenyl as the internal standard. cTemperature (125 oC). dPO (21.4 mmol), catalyst (60 mg),
CO2 pressure (1.0 MPa), reaction time (1.5 h), temperature (110 °C).
This unique phase behaviour and structure were much useful in the
cycloaddition reaction of CO2 with epoxides. Due to the ring-opening of epoxides
assisted by the hydrogen bond, all the CABFILs exhibited higher PC yield than the
46 | P a g e
butylpyridinium bromide ([BPy]Br) without carboxyl group (Table 2.1, entries 2-5 vs.
1). Compared with the other CABFILs, 2a was observed the highest activity.
Considering that 2a could only partly transformed to precipitate at room temperature,
3a was chosen as the optimal catalyst for further investigation. The comparison of
the catalytic activity of 3a with our previously reported acid–based bifunctional ILs
was also displayed in Table 2.1. 3a exhibited much higher activty than the
bipyridinium- and isonicotinic-based functionalized ILs (entry 6 vs. 7, 8). 3a exhibited
much higher activity than the bipyridiniumand isonicotinic-based functionalized ILs
(entry 6 vs 7, 8). We also compared catalytic activity of 3a with the most efficient
metal-free heterogeneous catalysts (TOFs = 90 h−1) at the same conditions. Then,
the reaction conditions such as influence of temperature, CO2 pressure, reaction
time and dosage of catalysts on the cycloaddition reactions of CO2 with PO were
investigated to find the most appropriate and efficient reaction conditions (Figure
2.12-2.15). The results indicated that nearly 92% yield of PC together with 99%
selectivity was obtained at 130 °C, 2.0 MPa in 20 min (TOFs = 276 h−1), which was
much higher than the most efficient metal-free heterogeneous catalysts at the same
conditions.
Fig. 2.12 Effect of pressure. Reaction conditions: PO (14.3 mmol), catalyst (1.0mol%),
reaction time (1h), temperature (120oC).
0.5 1.0 1.5 2.0 2.5 3.0
20
30
40
50
60
70
80
90
Yield (%)
Selectivity (%)
Yie
ld a
nd s
ele
ctivity (
%)
Pressure (MPa)
47 | P a g e
Fig. 2.13 Effect of temperature Reaction conditions: PO (14.3 mmol), catalyst (1.0 mol%),
CO2 pressure (2.0 MPa), reaction time (1 h).
Fig. 2.14 Effect of reaction time Reaction conditions: PO (14.3 mmol), catalyst (1.0 mol%),
CO2 pressure (2.0 MPa), temperature (130oC).
100 110 120 130 140
40
50
60
70
80
90
100
Yield (%)
Selectivity (%)
Yie
ld a
nd
se
lectivity (
%)
Temperature (oC)
0 20 40 60 80
20
30
40
50
60
70
80
90
100
Yield (%)
Selectivity (%)
Yie
ld a
nd s
ele
ctivity (
%)
Time (h)
48 | P a g e
Fig. 2.15 Effect of catalyst amount. Reaction conditions: PO (14.3 mmol), CO2 pressure
(2.0 MPa), reaction time (20min), temperature (130oC).
Figure 2.16 Reuse of catalyst 3a. Reaction conditions: PO (14.3 mmol), catalyst (1.0
mol%), CO2 pressure (2.0 MPa), temperature (130oC), reaction time (20 min).
Recycling experiments showed that 3a could be reused four times with high
activity and selectivity (Figure 2.16). During the cycle experiments, the catalysts
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
30
40
50
60
70
80
90
Yield (%)
Selectivity (%)
Yie
ld a
nd s
ele
ctivity (
%)
Weight (mol%)
1 2 3 4
0
20
40
60
80
100
PC yied PC selectivity
Yie
ld a
nd s
ele
ctivity (
%)
Run Times
49 | P a g e
were easily recovered by simple filtration at room temperature, and then directly
used for the next cycle.
Figure 2.17 The TGA analysis of the catalysts (fresh and reused four times).
The thermogravimetric curve (Figure 2.17) showed no significate change after
4 times usage, which proved the high stability of the catalyst activity.
Figure 2.18 Reaction conditions: epoxides (14.3 mmol), catalyst (1.0 mol%), CO2
pressure (2.0 MPa), temperature (130oC), time (20min).
0 100 200 300 400 500
-0.2
0.0
0.2
0.4
0.6
0.8
1.0W
eig
ht
(%)
Temperature (oC)
UsedFresh
5a 5b 5c 5d 5e
0
20
40
60
80
100
120
6e6d6c6a
99%95%
85%86%
Substrates
O
OO
O PhO
OO
O
OO
Cl
O
OO
O
OO
C6H13
Yie
ld (
%)
92%
6b
50 | P a g e
Figure 2.19 Reaction conditions: PO (14.3 mmol), catalyst (1.0 mol %), CO2 pressure (0.1
MPa), and temperature (50 °C).
A battery of epoxide substrates was examined for the synthesis of
corresponding cyclic carbonates to test the adaptability of 3a to different epoxides.
As shown in Figure 2.18, 3a was suitable for a variety of terminal epoxides and
exhibited high yield of the corresponding cyclic carbonates. Among all the epoxides
surveyed, the activity of 5e was the highest, with 99 % yield of 6e achieved in 20
min.
To achieve the goal of finding an efficient catalyst that can react at mild
conditions, 3a catalysed cycloaddition of CO2 5c/5e were carried out under
atmospheric pressures of CO2 (0.1MPa) with a catalyst loading of 1 mol %, and the
reaction was run at 50°C. As shown in Figure 2.19, a 71% yield of 6c and 95% yield
of 6e could be obtained within 20 h at this CO2 pressure and temperature.
51 | P a g e
Scheme 2.2 Proposed mechanism for cyclic carbonates synthesis catalyzed by 3a.
Figure 2.20 Potential energy surface profiles of the 3a-catalyzed process and the
optimized geometries for the intermediates and transition states. See the APPENDICES
for computational details.
52 | P a g e
According to the reports and results above, a possible mechanism for fixation
of CO2 with epoxides was illustrated in Scheme 2.2, and we chose 3a as a
representative to study the mechanism details through DFT study (Figure 2.20). As
shown in Scheme 2.2 and Figure 2.20, firstly, 3a and PO interacted to form a
complex A, and then epoxy ring-opening step made A convert into intermediate B
via transition state TS1 with a barrier of 14.0 kcal/mol. A new complex C was formed,
when CO2 was added into the reaction system. Then, nucleophilic attack of the
intermediate on the complex C produced the alkyl carbonate D through TS2 with a
lower energy barrier of 2.9 kcal/mol. Finally, the cyclic carbonate was obtained by
intramolecular ring-closure and the catalyst was regenerated (TS3). The ring-
closure step was the rate limiting step with the highest energy barrier of 21.4
kcal/mol (TS3). The difference between ring-closure and ring-opening step was 7.4
kcal/mol. This could be attributed to the hydrogen bond-assisted ring-opening of
epoxide, which made the ring-opening much easier. Besides, there was some
negative effect of hydrogen bonding on the ring-closing event.
2.5 Conclusions
In summary, a series of carboxylic acid–based functional ionic liquids (CABFILs)
were facilely prepared by one-step synthesis method. They displayed reversible
temperature-controlled phase transitions in PC, which was much useful for the
coupling reaction and separation processes. CABFILs were successfully used in
reaction-separation for conversion of CO2 to carbonates under metal- and solvent-
free conditions. Besides, the IL 3a displayed high activity, and nearly 92% PC yield
was obtained within 20 min and could be readily separated by filtration at room
temperature for easy recycle. More importantly, 3a was suitable for a variety of
terminal epoxides. This approach helps to avoid further waste of the subsequent
separation step, as well as a highly effective way to combine the benefits of
heterogeneous and homogenous catalysts, which is of great interest from the
viewpoint of energy saving and chemical engineering.
53 | P a g e
Chapter 3: Efficient Transformation of CO2 to Cyclic
Carbonates by Bifunctional Protic Ionic Liquids under
Mild Conditions
3.1 Introduction
Carbon dioxide is one of the main components of flue gas, which is responsible
for the global warming. CO2 is also regarded as an abundant, nontoxic and
renewable C1 resource. [20–23] The utilization of CO2 as raw materials for
production of energy carriers and chemicals is a promising alternative, which can
reduce greenhouse gas thus alleviate the impact of climate change, whilst producing
various organic chemical commodities.[24–26,206–208] However, applications
related to CO2 are limited because of its thermodynamic stability and therefore the
CO2 activation always requires electrolytic reduction processes or high-energy input.
[27] One of the typical feasible routes is the synthesis of five-membered cyclic
carbonates by cycloaddition of CO2 with epoxides. As one of a few successfully
industrial products that efficiently utilize CO2 as a carbon feedstock, cyclic carbonate
can be wildly used as solvents in chemical processes,[33–35] electrolyte
components in lithium batteries,[36] useful monomers for acyclic carbamates[37,38]
and carbonates,[39] and intermediates in the production of fine chemicals, etc.
[40,41]
To date, various catalysts have been developed for the synthesis of useful
cyclic carbonates from CO2 and epoxides, such as metal-based catalysts, [24–
34]organocatalysts,[76,93,123,214–220] and ionic liquids etc.
[12,117,145,171,172,221–224]Although most of the catalyst systems show a good
yield to produce carbonates, high temperatures (>100 °C) and/or high CO2
pressures are always needed in these studies. Hence, great efforts have been
focused on the development of efficient and sustainable catalyst systems that can
be carried out chemically converting CO2 at relatively mild reaction conditions. In
this respect, many catalysts have been synthesized and exhibited a good
performance in the synthesis of cyclic carbonates from CO2. Metal−based catalysts
including metal-organic framework (MOF),[70,151] metal (salen) complex[225,226]
54 | P a g e
and metal-porphyrins[152–154] were reported to have a good yield of cyclic
carbonates at atmospheric pressure and/or room temperature for the activity sites
of metal ions and halide ions. For example, North and co-workers reported an Cr(III)
salphen complexes for the cycloaddition reaction under ambient conditions with the
presence of TBAB (tetrabutylammonium bromide).[147] The catalyst could catalyze
CO2 and epoxides to cyclic carbonates in 57−92% isolated yields after a reaction
time of 24 hours. Organocatalyst systems, such as boronic acids,[96]
tetraarylphosphonium salts (TAPS)[227] and pyridine-methanol/onium salts,[155]
could promote the cycloaddition of CO2 with epoxides under a moderate condition
due to the activation of epoxides by hydrogen bond (H-bond). Ionic liquids with a
strong hydrogen bond donor (HBD) were widely reported for this reaction. Aitor and
Israel et al[158] reported an imidazolium based iron-containing ionic liquid, and it
showed quantitative conversion and 94% chemoselectivity for the cycloaddition of
CO2 to epoxides under near ambient conditions. Park et al[160] developed a
pyridinium ILs-decorated MOF and used as solvent-free catalyst for CO2-oxirane
coupling reactions. The best catalyst displayed a high catalytic activity under 60 oC
and 1.2 MPa CO2 because of the synergetic effect of the IL functional sites. In
addition, we also demonstrated carboxylic acid-based ionic liquids that could
promote the cycloaddition reaction of CO2 at 50oC and 0.1MPa.[12] Recently studies
have been focused on protic ionic liquids, which exhibited not only excellent ability
of reversible CO2 capture but also highly efficient CO2 chemical conversion even
under ambient conditions because of the powerful H-bonding.[166–168] For
example, Han et al [169] employed a novel dual-ionic liquid system for cycloaddition
of epoxides with CO2 under temperature from 30 to 60 °C at 1 atm, the results
showed excellent yields without any solvents. However, compared to high
temperature and pressure catalysts, unsatisfactory activities and long reaction time
(>20h), presence of metals and/or toxic solvents are still drawbacks that need to be
overcome. It is a great challenge that designing efficient, green and metal-free
catalysts toward effective CO2 conversion under mild conditions.
55 | P a g e
Figure 3.1 ILs used in this study.
Inspired by these works, we reported here the synthesis of DBU-based
bifuncitional protic ionic liquids (DBPILs) by acid-base reaction at room temperature
based on good acidity of halogenated carboxylic acid and alcohols that caused by
inductive effect of the electron-withdrawing group (Figure 3.1). DBPILs that
composed by alkoxy anion, protic acid and nucleophilic groups were successfully
used in cycloaddition reaction of CO2 with epoxides at 1 bar CO2 and 30/50 oC. We
found that they were efficient metal-free catalysts for this reaction, which displayed
high activity in producing carbonates without the need for long reaction time or co-
catalyst. And we explored the influence of the substrate scope on the catalytic
behaviour with various epoxides and simulated flue gas. DFT studies, IR spectrum
and experiments were conducted to study mechanism of the activation of CO2 and
H-bond interaction between DBPILs and epoxide.
3.2 General information
Carbon dioxide and nitrogen were supplied by Beijing Analytical Instrument
Factory with a purity of 99.99% and 99.999% separately. Simulated flue gas was
made by controlling the gas flow rate (CO2:N2=3:17) using gas flowmeter. 1,8-
diazabicyclo-[5.4.0]undec-7-ene (DBU 99%), 4-dimethylaminopyridine (99%),
bromoethane (98%), bromoacetic acid (98%), 2-bromoethanol (95%), 1,3-dibromo-
2-propanol (95%), 4-bromophbenol (98%), 1-butyl-3-methylimidazolium bromide
(97%) and all of the epoxides unless otherwise specified were bought from Aladdin
56 | P a g e
Reagent Co. Glycidyl phenyl ether was bought from TCI Shanghai. Lithium
Bis(trifluoromethanesulphonyl)imide and ethylacetate were bought from Sinopharm
Chemical Reagent Co., Ltd, and were used without further purification. All
calculations were carried out with B3LYP-D3/6-31+G** level implemented in
Gaussian 09 package. The Cartesian coordinates can be found in APPENDICES.
3.3 Experimental section
3.3.1 Synthesis of catalysts
To synthesize the protic ionic liquids, electron withdrawing groups are selected
to increase acidity of alcohols and carboxylic acid through inductive effect. Halogens
are well known as electron-withdrawing groups. It has been proven that Br- is an
excellent nucleophilic ion for the cycloaddition reaction in our previous
work.[145,223] Herein, halogenated carboxylic acid and alcohols with a short chain
length (the closer of the halides and acid, the stronger inductive effect) are chosen
to react with super base DBU. During the experiments, a series of DBPILs
composed by protonic acid and nucleophilic groups was prepared by acid-base
neutralizing reaction at room temperature. DBU based ionic liquid with a phenolic
hydroxyl group (1d) was prepared by DBU and 4-bromophbenol due to the weak
acidity of 4-bromophbenol attributed to the conjugative effect and the long chain
length between bromide and hydrogen group (Details are shown in supporting
information Scheme 3.1). 4-dimethylaminopyridine (DMAP) based ILs (1e) were
synthesized according to the literature[228] (Scheme 3.2). DBU-based catalysts 1g
with NTF2 was synthesized with ion-exchange method (Scheme 3.3).
Scheme 3.1 One step synthesis of catalysts in this study.
All of the DBU-based catalysts with bromide were synthesized by using one-
step method. 1b was chosen as a model to show the process. In a typical reaction,
bromoacetic acid (20.00 mmol) was dissolved in ethyl acetate. Then DBU (40.00
57 | P a g e
mmol) was dropped into the flask. The mixture was stirred for an hour at room
temperature. After the reaction, the top phase was immediately poured out and the
residue liquid was washed three times with ethyl acetate in separatory funnel and
dried at 50oC for 24 h under vacuum. Finally, a viscous liquid was obtained.
Scheme 3.2 One step synthesis of catalyst 1e.
4-dimethylaminopyridine (DMAP) based ILs (1e) were synthesized according
to the literature[228]. In a typical reaction, DMAP (50.00 mmol) and 2-bromoethanol
(60.00 mmol) were dissolved in ethyl acetate and added into a 250 mL three-necked
flask. The mixture was stirred for 12 h at 50 oC. When it is cool down, the top phase
was poured out and the solid was washed three times with ethyl acetate and dried
at 50oC in a vacuum oven for one day.
Scheme 3.3 Synthesis of catalyst 1g in this study.
DBU-based catalysts 1g with NTF2 was synthesized by using ion-
exchange method. In a typical reaction, 1f (4.00 mmol) was added into a 250 mL
flask and dissolved in water. Then Lithium Bis(trifluoromethanesulphonyl)imide
(10.00 mmol) was poured into the flask. The mixture was stirred for 24 h at room
temperature. After the reaction, the top phase was poured out and the residue was
washed n three times with water in separatory funnel. Then the product was dried
at 50oC for 24 h under vacuum.
58 | P a g e
3.3.2 Characterization of the catalysts
The morphology was observed through a scanning electron microscope (JEOL
JSM 6700F). Fourier transform infrared (FT-IR) spectra were recorded on a Thermo
Nicolet 380 spectrophotometer with anhydrous KBr as standard (Thermo Electron
Co.). NMR spectra were recorded on a Bruker AVANCE III HD 600 spectrometer
with DMSO-d6 as solvent.
3.3.3 Procedure of the cycloaddition reaction of CO2 with epoxide
Figure 3.2 Photographic image shows the process of the reaction
The coupling reaction of carbon dioxide and epoxide was carried out in a 20 mL
Schlenk tube with a magnetic stirrer and an automatic temperature control system.
In a typical reaction, 0.5ml of epichlorohydrin and appropriate amounts of catalyst
were charged into the reactor at room temperature. Then, a balloon of CO2 was
connected to the schlenk tube, control the temperature within the desired range
afterwards. After the reaction, the remaining CO2 was vented out slowly. The yield
of the products was characterized by HNMR spectroscopy of the crude reaction
mixture by using CDCl3 as solvents.
3.3.4 Recycle experiment
After the reaction, 10 ml water was poured in to the schlenk tube to wash the
product. The mixture was stirred for 1 h at room temperature. The product was
59 | P a g e
separated from the mixture by filtration and washed one more time with water.
Afterwards, the product was dried at 80 oC for 24 h under vacuum. The yield of the
product was calculated by weight. The liquid phase was first separated with 2f in a
separatory funnel. Then water was removed by vacuum distillation. The obtained
catalysts were washed three times by ethyl acetate and dried at 50oC for 24 h under
vacuum, and ready for the recycling experiment.
3.3.5 Characterization of the catalysts and cyclic carbonates
Characterization of the catalysts
DBU:
Liquid:1H NMR (600 MHz, DMSO): 3.14 (dd, J = 10.8, 3.7 Hz, 4H), 3.09 – 3.04
(m, 2H), 2.27 – 2.21 (m, 2H), 1.64 (dq, J = 8.1, 5.9 Hz, 2H), 1.57 (ddd, J = 11.0, 5.6,
2.0 Hz, 2H), 1.54 – 1.45 (m, 4H). 13CNMR (151 MHz, DMSO): 159.50, 51.75, 47.44,
43.45, 36.33, 29.02, 28.06, 25.74, 22.31.
1a:
Solid powder:11H NMR (600 MHz, DMSO): δ 3.68 – 3.62 (m, 2H), 3.57 (q, J =
7.2 Hz, 2H), 3.48 (dt, J = 17.0, 5.8 Hz, 4H), 2.92 – 2.86 (m, 2H), 2.04 – 1.90 (m, 2H),
1.74 – 1.67 (m, 2H), 1.67 – 1.58 (m, 4H), 1.16 (t, J = 7.2 Hz, 3H). 13C NMR (151
MHz, DMSO):165.67, 53.86, 48.41, 48.08, 45.87, 27.69, 27.00, 25.46, 22.65, 19.61,
13.58.
1b:
Viscous solid: 1H NMR (600 MHz, DMSO): δ 9.69 (s, 1H), 3.55 (dd, J = 19.5,
15.0 Hz, 4H), 3.49 (t, J = 5.8 Hz, 4H), 3.30 (d, J = 31.3 Hz, 2H), 3.25 (t, J = 5.7 Hz,
4H), 2.80 – 2.57 (m, 4H), 2.02 – 1.85 (m, 4H), 1.72 – 1.65 (m, 4H), 1.65 – 1.57 (m,
8H). 13C NMR (151 MHz, DMSO): 165.37, 53.36, 47.87, 37.52, 31.59, 28.19, 25.89,
23.28, 18.84.
1c:
Slid: 1H NMR (600 MHz, DMSO): δ 9.67 (s, 1H), 3.60 – 3.54 (m, 4H), 3.50 (t, J
60 | P a g e
= 5.8 Hz, 4H), 3.33 (s, 2H), 3.26 (t, J = 5.7 Hz, 4H), 2.78 – 2.62 (m,4H), 1.96 – 1.87
(m,4H), 1.72 – 1.65 (m, 4H), 1.65 – 1.57 (m, 8H). 13C NMR (151 MHz, DMSO):
165.35, 53.63, 48.18, 37.48, 31.52, 27.89, 25.66, 23.29, 19.13.
1d:
Slid: 1H NMR (600 MHz, DMSO): δ 12.04 (s, 1H), 7.30 – 6.89 (m, 2H), 6.61 –
6.45 (m, 2H), 3.34 (dd, J = 11.4, 6.9 Hz, 2H), 3.31 (t, J = 5.9 Hz, 4H)., 3.16 (t, J =
5.6 Hz, 2H), 1.83 – 1.75 (m, 2H), 1.65 – 1.57 (m, 2H), 1.57 – 1.49 (m, 4H). 13C NMR
(151 MHz, DMSO): δ 163.52, 162.08, 131.48, 118.69, 105.41, 52.63, 47.65, 32.87,
28.56, 26.77, 24.33, 20.22.
1e:
Slid: 1H NMR (600 MHz, DMSO) δ 8.35 (t, J = 5.4 Hz, 1H), 8.18 (dd, J = 5.7,
1.4 Hz, 1H), 7.15 – 6.95 (m, 1H), 6.80 (dd, J = 5.7, 1.5 Hz, 1H), 4.37 (t, J = 6.6 Hz,
1H), 3.30 (s, 1H), 3.19 (s, 3H), 3.08 (s, 2H), 2.83 (t, J = 6.6 Hz, 1H). 13C NMR (151
MHz, DMSO): 172.00, 155.82, 155.49, 143.85, 142.34, 107.40, 106.80, 52.89,
35.26.
1f:
Slid: 1H NMR (600 MHz, DMSO): δ 9.61 (s, 1H), 3.64 – 3.53 (m, 6H), 3.49 (t, J
= 5.8 Hz, 6H), 3.30 (s, 4H), 3.26 (t, J = 5.7 Hz, 6H), 2.75 – 2.65 (m, 6H), 2.09 (s,
1H), 1.96 – 1.86 (m, 6H), 1.73 – 1.65 (m, 6H), 1.65 – 1.54 (m, 12H). 13C NMR (151
MHz, DMSO): 165.39, 53.38, 47.89, 37.53, 31.60, 28.19, 25.89, 23.29, 18.85.
1g:
Liquid: 1H NMR (600 MHz, DMSO): δ 9.61 (s, 1H), 3.64 – 3.53 (m, 6H), 3.49 (t,
61 | P a g e
J = 5.8 Hz, 6H), 3.30 (s, 4H), 3.26 (t, J = 5.7 Hz, 6H), 2.75 – 2.65 (m, 6H), 2.09 (s,
1H), 1.96 – 1.86 (m, 6H), 1.73 – 1.65 (m, 6H), 1.65 – 1.54 (m, 12H). 13C NMR (151
MHz, DMSO): 165.39, 53.38, 47.89, 37.53, 31.60, 28.19, 25.89, 23.29, 18.85.
Spectra of product 1H NMR and 13C NMR of Products:
4-chloromethyl-1, 3-dioxolan-2-one:
1H NMR ((CDCl3, TMS, 400 MHz): 3.84 (d, J = 6.0 Hz, 2H), 4.05 (t, J = 8.4 Hz,
1H), 4.60 (t, J = 8.0 Hz, 1H), 5.07–5.10 (m, 1H). 13C NMR (CDCl3, TMS, 100 MHz):
44.15, 70.46, 73.51, 154.94.
3a:
1H NMR ((CDCl3, TMS, 400 MHz): 3.84 (d, J = 6.0 Hz, 2H), 4.05 (t, J = 8.4 Hz,
1H), 4.60 (t, J = 8.0 Hz, 1H), 5.07–5.10 (m, 1H). 13C NMR (CDCl3, TMS, 100 MHz):
44.15, 70.46, 73.51, 154.95.
3b:
1H NMR ((CDCl3, TMS, 400 MHz): 1.63 (s, 3H), 3.67 (d, J = 11.57 Hz, 1H), 3.75
(d, J = 12.1 Hz, 1H), 4.21 (d, J = 8.8 Hz, 1H), 4.53 (d, J = 8.8 Hz, 1H). 13C NMR
(CDCl3, TMS, 100 MHz): 44.15, 70.46, 73.51, 154.95.
3c:
1H NMR (CDCl3, TMS, 400 MHz): 3.63 (dd, J = 4.0, 11.2 Hz, 1H), 3.70 (dd, J =
4.0, 11.2 Hz, 1H), 4.02–4.11 (m, 2H), 4.41 (dd, J = 6.4, 8.0 Hz, 1H), 4.51 (dd, J =
8.4, 8.4 Hz, 1H), 4.79–4.85 (m, 1H), 5.22–5.32 (m, 2H), 5.83–5.93 (m, 1H); 13C NMR
(100 MHz, CDCl3) δ 65.9, 68.6, 72.0, 75.0, 117.1, 133.5, 154.8.
3d:
1H NMR (CDCl3, TMS, 400 MHz): 4.34 (t, 1H, J = 8.4 Hz); 4.80 (t, 1H, J = 8.4
Hz); 5.68 (t, 1H, J = 8.0 Hz); 7.35–7.44 (m, 5H); 13C NMR (CDCl3, TMS, 100 MHz):
71.10, 77.92, 125.81, 129.12, 129.63, 135.70, 154.81
62 | P a g e
3e:
1H NMR (CDCl3, TMS, 400 MHz): 0.88 (t, J = 7.5 Hz, 1H), 1.32 (dq, J = 14.8,
7.4 Hz, 2H), 1.42 – 1.56 (m, 2H), 3.46 (t, J = 6.5 Hz, 2H), 3.56 (dd, J = 11.5, 4.2 Hz,
1H), 3.63 (dd, J = 11.5, 2.7 Hz, 1H), 4.25 (dd, J = 8.3, 5.9 Hz, 1H) 4.52 (t, 3J = 8.4
Hz, 1H), 4.91 (dddd, J = 8.6, 6.0, 4.1, 2.8 Hz, 1H), 13C NMR (CDCl3, TMS, 100 MHz):
13.55, 18.63, 31.06, 66.00, 69.52, 70.54, 75.48, 154.88.
3f:
1H NMR (CDCl3, TMS, 400 MHz): 4.15 (dd, 3J = 4.4 Hz, 2J = 10.8 Hz, 1H), 4.24
[dd, 3J = 3.6 Hz, 2J = 10.8 Hz, 1H), 4.55 (dd, 3J = 8.4 Hz, 2J = 6 Hz, 1H), 4.62 (t,
3J = 8.4 Hz, 1H), 5.03 (m, 1H), 6.91 [d, 3J = 8.0 Hz, 2H), 7.08 (s, 1H), 7.31 (t, 3J =
8.0 Hz, 2H). 13C NMR (CDCl3, TMS, 100 MHz): 66.17, 68.84, 74.11, 114.57, 121.92,
129.62, 154.65
3g:
1H NMR (CDCl3, TMS, 400 MHz): 2.13 (s, 3H), 4.18 (dd, J = 11.2, 3.5 Hz, 1H),
4.27 (dd, J = 11.2, 2.4 Hz, 1H), 4.47 (dd, 3J = 8.4 Hz, 5.2Hz, 1H), 4.64 (t, 3J = 8.5
Hz, 1H), 5.17 (m, 1H), 6.88 (td, J = 7.4, 0.8 Hz, 1H), 6.93 (d, J = 7.8 Hz, 1H), 7.14-
7.17 (m, 2H). 13C NMR (CDCl3, TMS, 100 MHz): 15.49, 66.17, 68.84, 74.11, 114.57,
121.92, 129.62, 154.65
3h:
1H NMR (CDCl3, TMS, 400 MHz): 1.52 – 1.55 (m, 2H), 3.46 (t, J = 5.9 Hz, 2H),
3.55 (dd, J = 11.5, 4.2 Hz, 1H), 3.63 (dd, J = 11.5, 2.7 Hz, 1H), 4.25 (dd, J = 8.2 5.9
Hz, 1H) 4.52 (t, 3J = 8.4 Hz, 1H), 4.91 (dddd, J = 8.6, 5.9, 4.2, 2.8 Hz, 1H), 13C NMR
(CDCl3, TMS, 100 MHz): 25.60, 66.09, 69.51, 70.55, 75.50, 154.93.
63 | P a g e
3.4 Results and discussion
3.4.1 Activities of various catalysts
The catalytic activities of various DBPILs were carried out with epichlorohydrin
and 1 bar of CO2 (balloon) in a schlenk tube at 30 °C. The results were shown in
Table 3.1. It was found that the common ILs [bmim]Br (Table 3.1, entry 1) had a low
activity in catalysing the reaction. Interestingly, DBU-based ILs without protonic acid
(1a) was observed a similar activity with [bmim]Br (Table 3.1, entry 2 vs 1), which
indicated that cation may have little effects on the reaction. Then the activity of DBU-
based ILs composed by protic acid and bromine ion (1b and 1c) was studied at the
same conditions, and showing a very high yield of chloropropene carbonate (CPC)
(70% and 76% respectively) as compared to 1a that without protic acid (Table 3.1,
entry 3, 4 vs 2). The possible reason maybe that the protic acid of DBPILs could
activate epichlorohydrin efficiently by the powerful H-bond interaction. Besides, as
a nucleophilic anion, alkoxy anion might play the same role with Br-, which could
increase the active site.
Table 3.1: Reactions of CO2 with epichlorohydrin catalyzed by different ILsa
Entry Catalyst Time (h) Yieldb (%)
1c [Bmim]Br 6 23
2 1a 6 26
3 1b 6 70
4 1c 6 76
5 1d 6 14
6 1e 6 47
7 1f 6 92
8 1g 10 4
9d 1f 10 91
aReaction conditions: epichlorohydrin (0.5ml), ILs (6 mol%), 1 bar of CO2 (balloon),
Temperature (30oC). bDetermined by 1H NMR. cCatalstys (8 mol%), d Catalyst ( 4 mol %),
Temperature (25oC).
To compare the effect of H-bond interaction, DBU based ionic liquid with a
64 | P a g e
phenolic hydroxyl group (1d) was prepared by DBU and 4-bromophbenol. Even
phenolic hydroxyl group was reported a good HBD[229,230], but in this study, 1d
only showed a low activity of 14%. 4-dimethylaminopyridine (DMAP) based ILs (1e)
with a hydroxyl group, which had been reported as an efficient catalyst for this
reaction in our previous work,[12] was also investigated (Table 3.1, entry 6). 1e
showed a promising yield of CPC (47%) for the hydroxyl group activating
epichlorohydrin (Table 3.1, entry 6 vs 1, 2), but much lower than DBU based protic
ionic liquids (DBPILs). The possible mechanism was speculated that hydrogen
proton from DBPILs had a stronger H-bond interaction with epoxide than –OH group
from 1e, which made the ring open of epoxide much easier, and resulted in the
higher activity of DBPILs compared to 1e (Table 3.1, entries 3, 4 vs 6). Then, DBPILs
1f incorporated with protonic acid and multi-nucleophilic sites was prepared and
used for this reaction. It showed the highest CPC yields of all the catalysts at the
same conditions with aforementioned studies (Table 3.1, entry 7). To find whether
alkoxy anion can play the same role with bromine ion, DBPILs 1g without bromine
ion was prepared and used in this reaction. Only 4% yield of CPC was obtained
after 10 hours as shown in Table 1 (Entry 8), which demonstrated that the alkoxy
anion had little effect on catalytic performance of this reaction. Surprisingly, 1f
showed a 91% yield of CPC within 10 hours at room temperature (Table 3.1, entry
9), while the reported pincer-type compounds catalysts,[231] which had the highest
TON and/or TOF for organocatalysts under ambient conditions, took 24 hours to
reach 92% yield of CPC. In view of this, 1f was chosen as benchmark catalyst to
investigate influence of reaction parameters.
3.4.2 Effect of reaction conditions
The effects of reaction time and temperatures were presented in Figure 3.3.
The yields of CPC increased rapidly to 82% within the first 4 h at 30 oC, and then
slowly reached to 96% in the next 4 hours. The results indicated an obviously
decrease of reaction rates. As the reaction temperature increased to 50 oC, the yield
of CPC increased to 98% sharply in 4 h without an obvious slow-growth stage. This
may be caused by the increasing viscosity of the reaction system with the producing
of CPC, which have a negative effect on the CO2 transferring in the liquid phase.
The mechanism mentioned above was confirmed by the same behaviour of the
65 | P a g e
catalyst loading study shown in Figure 3.4, which also had a slow-growth stage with
the increasing of 1f.
Figure 3.3 Effects of reaction time and temperature catalyzed by 1f. Reaction conditions:
epichlorohydrin (0.5ml), ILs (6 mol%), CO2 (balloon).
Figure 3.4 Effects of catalyst amount catalyzed by 1f. Reaction conditions:
epichlorohydrin (0.5ml), CO2 (balloon), temperature (30 oC), time (8 h).
0 2 4 6 80
20
40
60
80
100
Time (h)
30 oC
50 oC
Yie
ld (
%)
0 2 4 6 840
60
80
100
Yie
ld (
%)
Amount (%)
66 | P a g e
3.4.3 Catalytic activity of epoxides with simulated flue gas and
SO2
Figure 3.5 Cycloaddition of epichlorohydrin with simulated flue gas (a) and SO2 (b)
catalysed by 1f, and photographic image show the phase change of 1f after the
absorption of SO2 (c).
CO2 is known as the main component of dry flue gas. More attentions has been
paid on the conversion of CO2 from the flue gas.[20,150,212] In order to investigate
whether DBPILs could be used in the flue gas, a 15% CO2/85% N2 system was
chosen to simulate flue gas for the cycloaddition reaction with epoxides (Figure 3.5).
However, only 24% of CPC was obtained within 6 hours catalysed by 1f, which was
much lower than pure CO2 at the same conditions (24% vs 92%). The yield of CPC
can reach to 91% after 36 hours reaction. The results indicated the feasibility for
conversion of CO2 in the flue gas catalysed by DBPILs, but the comparably low
activity was still the drawback need to be overcome. Then we change the flue gas
to SO2 (another component of flue gas), catalyst 1f exhibited extremely high activity
(Figure 2.5 b), a 96% of 4f could be obtained within half an hour at room temperature.
The most important reason was that SO2 was much more activity than CO2.
Furthermore, when we did the experiments, we found that 1f would transfer from
solid to liquid after the absorption of SO2 (See Figure 2.5 c). Then, the SO2
absorptivity of 1f was investigated by experiment. The results showed that 1f could
show a high SO2 capacity of 1.1g SO2 per gram 1f (12 mol SO2/1f).
67 | P a g e
3.4.4 Catalytic activity to various epoxides
Table 3.2: Reaction of CO2 with substrates catalysed by 1fa
30oC, 6%, 6h, 3a: 88% 3%, 6h, 3b: 65% 3%, 6h, 3c: 94%
6%, 6h, 3d: 87% 2%, 12h, 3e: 89% 6%, 6h, 3f: 97%a,
95%b
3%, 8h, 3g: 97% 3%, 8h, 3h: 84%
aYields were determined by NMR. bIsolated yields were determined by weighting.
A range of different substituted terminal epoxides were examined under a
balloon of CO2 condition in the presence of 1f DBPILs. The results were summarized
in Table 3.2. Epibromohydrin (2a) could afford the product 3a in a good yield of 88%
at the optimal condition. Taking into account of the industrial application, the loading
of 1f was reduced, and the reaction temperature increased to 50oC. However, the
carbonate 3b showed much lower yield than 3c at the same condition, which
probably due to the high stereo-hindrance effect. Furthermore, styrene oxide 2d and
glycidol derivatived 2e-2h were examined. All of these epoxides generated the
corresponding cyclic carbonates in good yields (3d-3h).
68 | P a g e
3.4.5 Recycling of the catalyst
Figure 3.6 Recycle experiments catalyzed by 1f. a Reaction conditions: 2f (0.5 ml), 1f (6
mol%), 1bar CO2 (balloon), Temperature (50 oC), Reaction time (6 h).
2f was subsequently chosen as an optimal terminal epoxide to study the
cycling performance of DBPILs 1f. When we tried to recycle 1f after the reaction,
we found that the yield of 3f decreased obviously from 95% to 77% after four runs
(Figure 3.6). Based on the report, the reduction of catalytic activity after used might
be caused by the partial loss of the catalyst for the sublimation property[166] or
catalyst addition to epoxides[158,227]. Then, a series of experiments were designed
to study the reason of the decreased activity. The experiments and spectrum results
indicated that the DBPILs 1f could addition to 2f and further generate 1h with a
hydroxyl group, because of the “super-dissociating” feature of the protic ionic
liquids.[232] Furthermore, 1h could not activate CO2 and had a relatively weak H-
bond interaction with epoxide compare to the powerful H-bonding of 1f, which led to
the reduction of the yields in the recycle experiments.
1 2 3 4
0
20
40
60
80
100
Yie
ld (
%)
Run times
69 | P a g e
Scheme 3.4. Mechanistic studies by experiments
A series of experiments were designed to study the reason of the low activity
(Scheme 3.4). The results indicated that the DBUPILs 1f would react with 2f to
produce 1h with a hydroxy group (Scheme 3.4 A). The structure of 1h was
demonstrated by NMR spectrum (Figure 3.7).
Figure 3.7 HNMR of 1f and 1h.
70 | P a g e
However, DBU based ILs 1a without a protonic acid could not react with 2f
(Scheme 3.4 B). The above results suggested that 1f could react with epoxide 2f to
generate 1h and DBU, leading to the unrecyclable of catalyst 1f and a low activity
of the catalyst system. The hydrogen proton and alkoxy anion might play key roles
in the reaction of DBUILs and epoxide. Subsequently, a probable mechanism of 1e
reacted with epoxide 2f was proposed. The detail was shown in the supporting
information (Scheme 3.5). First, the strong H-bond between DBUPILs and epoxide
led to the ring-open step (step 1), then the proton transfer (step 2) finally resulted in
the formation of 1g and DBU (step 3). These results also suggested that DBUPILs
were excellent epoxy ring-open catalysts at mild conditions, which could be widely
used in the other ring-open reaction of epoxide.
Scheme 3.5 probable mechanism of 1e reacted with epoxide 2f
In order to identify whether 1h was a reactive intermediate of the catalytic cycle.
First, 1h was submitted to the CO2 fixation conditions without epoxide, and no
carbonate 3f was obtained at all (Scheme 3.4 C). Next, we found 1h could catalytic
epoxide 2f to afford the corresponding carbonate 3f (Scheme 3.4 D), and 1h was
not changed at the end of the reaction. However, the yield of 3f catalyzed by 1h was
only 74%. By contrast, 1f exhibited an excellent yield of 3f (95%, Table 2) at the
same condition. The probable reason maybe that the H-bond interaction between –
OH group and epoxide was weaker than hydrogen proton. Then, the catalytic activity
of 1h mixed with DBU was studied to compare with 1f and 1h at the same condition,
because 1h and DBU were ring-open species during the cycloaddition reaction
catalyzed by 1f (Scheme 3.4 A). As compared to 1h, the 1h/DBU system had a 88%
yield of carbonate (Scheme 3.4 E), which was much higher than 1h (74%). This
might be caused by the absorption and activity of CO2 by DBU. But 1h/DBU system
71 | P a g e
had a lower activity than 1f (95%). The possible reason maybe that the hydrogen
proton from 1f could have a stronger H-bond interaction with epoxide than –OH
group from 1g, whilst alkoxy anion of 1f played the same role with DBU.
3.4.6 Studies of reaction mechanism
Figure 3.8 FT-IR spectra of the activation of CO2
FT-IR spectra were employed to identify whether alkoxy anion of 1f could
activate CO2. As shown in Figure 3.8, a new band at 1795 cm-1 appeared after the
reaction of CO2 with 1f, which corresponded to the new asymmetric (C=O) vibration
of the carbamate salt, thus implying the activation of CO2 by 1f.
3500 3000 2500 2000 1500 1000 500
In
ten
sit
y
Wavenumber (cm-1)
1f
1f+CO2
72 | P a g e
Figure 3.9 Comparisons of the relative energy of the ring-open step.
It is reported that H-bond interaction between catalyst and epoxide can reduce
the activation energy of ring-open step.[223] Hence, comparison of 1f and 1h
catalyzed ring-open step was examined by DFT study to identify whether hydrogen
proton from 1f had a more powerful H-bond interaction with epoxide than –OH group
from 1h. All calculations were carried out with B3LYP-D3/6-31+G** level
implemented in Gaussian 09 package. As shown in Figure 3.9, 1h-catalyzed ring-
open step has an energy barrier of 44.2 kcal/mol, which is a little higher than 1f-
catalyzed process (39.6 kcal/mol). The hydrogen atom of 1h is coordinated with the
oxygen of epoxide through a hydrogen bond leading to the length of the C–O bond
increased from 1.455 Å to 2.099 Å, which makes the ring-opening much easier. The
same interaction can be found from 1f and epoxide. The length of hydrogen protons
of 1f and oxygen of epoxide is closer than 1h (1.502 Å), the increased length of the
C–O bond caused by hydrogen bond of 1f and epoxide is a little longer (from 1.455
Å to 2.102 Å) than 1h. The results indicated a higher activity of 1f than 1h due to
the stronger H-bond interaction, which was well consistent with our experiment
results.
73 | P a g e
3.4.7 Probable mechanism for fixation of CO2 with epoxide
Figure 3.10 Potential energy surface profiles of 1f-catalyzed process and the optimized
geometries for the intermediates and transition states.
Based on all the results above, a possible mechanism of the 1f-catalyzed
process is proposed, and the DFT study was used to study the mechanism. As
shown in Scheme 3.6 and Figure 3.10, the H-bond interaction between 1f and
epoxide firstly made the length of C-O bond increased, which could improve the
ring-open process of epoxide (step 1). The attack of bromide ion to epoxide resulted
in the ring-open of epoxide and made A convert into intermediate B (step 2) via
transition state TS1 with a barrier of 39.6 kcal/mol. As CO2 was added into the
-30
-20
-10
0
10
20
30
40
En
erg
y(k
ca
l/m
ol)
0.0
A
TS1
BC
TS2
D
TS3
E
39.6
-5.3-8.4
2.9
-6.3
7.9
-23.6
74 | P a g e
reaction system, it could be activated by alkoxy anion, and led to the formation of
complex C (step 3). Subsequently, the alkyl carbonate D generated by the
nucleophilic attack of the intermediate through TS2 through a low energy barrier of
2.9 kcal/mol (step 4). Finally, the cyclic carbonate was obtained by ring-closure step
with an energy barrier of 7.9 kcal/mol (TS3). The study illustrated that the epoxy
ring-open step was a rate–limited step with the highest energy barrier of 39.6
kcal/mol (TS1).
Scheme 3.6. Mechanism of the cycloaddition reaction catalysed by 1f.
3.5 Conclusions
In summary, this work exhibits a simple way to prepare DBPILs by introducing
electron withdrawing groups to O-H acid. The DBPILs with protonic acid and
nucleophilic sites were used as single-component and metal-free catalysts in the
cycloaddition reaction of CO2 with epoxides at very mild temperature and 1 bar CO2
conditions. DBPILs showed a great improvement of catalytic activity and good
substrate compatibility to various epoxides. Furthermore, DBPILs were found
suitable for the conversion of simulated flue gas. The results from experiments,
spectrum and DFT illustrated the activation of CO2 of DBPILs and strong H-bond
75 | P a g e
interaction between DBPILs and epoxide. This study provides a high efficient epoxy
ring-open catalyst for transformation of CO2 with epoxide. The greatly improved
catalytic activity makes DBPILs a promising environmentally benign catalyst for the
applications of CO2 conversion at mild conditions.
76 | P a g e
Chapter 4: Aluminium-containing Ionic Liquid for
Cycloaddition of CO2 with Epoxides under Mild Conditions
4.1 Introduction
Carbon dioxide is considered as an abundant, easily available and renewable C1
building block.[20,23] As an efficient way for CO2 utilization, chemical conversion of CO2
has always been a hot question in not only academia but also international industry.[24–
26] However, CO2 conversion is limited because of its inherent thermodynamic stability,
thus resulting in low reactivity and high energy inputs. [27] Although CO2 is
thermodynamically stable, some progresses have been achieved in recent years[233].
One potentially useful strategy is the 100% atom-economical cycloaddition reaction of
CO2 and epoxides to five-membered cyclic carbonates (Scheme 4.1). [21,234,235]
Scheme 4.1 Synthesis of cyclic carbonates
In this context, the key issue to convert CO2 and epoxide into cyclic carbonates is
focused on the activation of CO2 and epoxides. Therefore, effective catalytic systems are
highly required. So far, many efficient catalysts have been developed for the cycloaddition
of CO2 and epoxides, such as metal containing complexes[71,74,75,85,147,209–213],
metal-organic framework (MOF),[70,151] metal (salen) complex[225,226] and metal-
porphyrins[152–154]), organocatalysts[76,93,96,123,155,214–220,227] and ionic
liquids.[12,117,145,158,160,171,172,221–224,236] However, high temperature and
pressure are generally needed. In recent years, researchers have paid much attention to
chemically convert CO2 with epoxides under mild reaction conditions, especially at
atmospheric pressure and room temperature. Though much progress has been made,
the chemical conversion of CO2 at atmospheric pressure and room temperature is still a
challenge. For example, the use of metal containing catalysts consisting of an
electrophilic metal ion and a nucleophilic halide ion will significantly accelerates the
process under mild conditions. [152,225,226] Andy Hor and Wu[225] reported a salen
based molecular cage complexed with Co and Al. These catalysts were found to be
efficient catalysts for the cycloaddition of CO2 with styrene oxide at 25 °C and 1 atm CO2.
77 | P a g e
Organocatalysts systems have also attracted increasing attentions to promote the
cycloaddition reaction of CO2 under a moderate condition because of the activation of
epoxides by a strong hydrogen bond donor, including boronic acids,[96] ascorbic acid[91]
and pyridine-methanol/onium salts [155] etc. Liu et al[231] reported series of pincer-type
compounds with a carboxyl group as proton transfer agent used to catalyze cycloaddition
of epoxides with CO2. These multifunctional catalysts were demonstrated the highest
TON and/or TOF for organocatalysts under room temperature and 1 bar of CO2. Ionic
liquids (ILs) have been widely reported in the cycloaddition reaction of CO2 under mild
conditions, because of the unique features such as high thermal and chemical stability,
easy recyclability, and turnable properties. Specifically, some ionic liquids with a strong
hydrogen bond donor (HBD) have displayed an excellent performance for this conversion
of CO2 to carbonates with epoxides under ambient conditions through carefully design of
activity sites and HBD.[158,165,168,236] For example, Han et al[169] prepared a novel
dual-ionic liquid system for cycloaddition of epoxide with CO2 under mild conditions (1
atm CO2, T = 30–60 °C), the results showed excellent yields without any solvents. Wang
et al [165] reported a dual hydroxyl functional mesoporous poly(ionic liquid)s as recyclable
heterogeneous catalysts for cyclic carbonate synthesis from CO2 and epoxides in the
presence of tetrabutylammonium iodide at 70 °C and 0.1/0.4 MPa. The catalyst could be
easily reused after stable activity.
Figure 4.1 Structure of catalyst used in this study
We have also found that by using DBU based bifunctional protic ionic liquids (DBPILs)
as metal and solvent-free catalysts, CO2 could react with epoxide at 30 oC and 1 bar CO2
and produce cyclic carbonates in excellent yields without the need for time-consuming
78 | P a g e
and co-catalyst because of the powerful hydrogen bond interaction (H-bonding) with
epoxides. However, the “super-dissociating” feature of the protic ionic liquids[232] made
the proton from DBPILs added to epoxide, and led to the reduction of the yields in recycle
experiments.
It is reported that electrophilic metal ion can significantly accelerate the process, and
aluminum has been illustrated a very powerful metal ion to activate epoxide[225]. Inspired
by this, a strategy was employed to solve the recycling of DBPILs by using aluminum ion
to replace proton from DBPILs. In this work, we designed a DBU based ionic liquids
containing aluminum (DILA) catalyst based on dissociating feature of proton from DBPILs
(Figure 4.1). DILA was successfully used to catalyze the cycloaddition reaction of CO2
with epoxides at 1 bar and room temperature. As a single component catalyst, this
DBPILs could show superior yield of carbonates with broad epoxide substrate scope
because the activate epoxides by the powerful aluminum ion and nucleophilic bromide
ion. Moreover, the DILA could be easily recovered and reused at least 4 times without
obviously activity loss.
4.2 Experimental section
4.2.1 General information
Carbon dioxide was supplied by Air Liquide Danmark with a purity of 99.995%. 1,8-
diazabicyclo-[5.4.0]undec-7-ene (99%), aluminum hydroxide, 3-bromopropionic acid
(97%), ethyl acetate (99.8%) and acetonitrile (99.8%) were bought from Sigma-Aldrich.
Tetrabutylammonium bromide and all of the epoxides unless otherwise specified were
bought from Aladdin Reagent Co. Glycidyl phenyl ether was bought from TCI Shanghai.
All of the solvents and chemicals were bought from Sigma-Aldrich, and were used without
further purification.
4.2.2 Synthesis of catalysts
DILA was synthesized by two-step method. Firstly, DBPILs was prepared according
to our previous work. In a typical reaction, the chosen amount of 3-bromopropionic acid
was dissolved in ethyl acetate, then 2 equivalents of DBU was dropped into the flask. The
mixture was stirred for an hour at room temperature. After the reaction, the residue solid
was separated by filtration, and washed three times with ethyl acetate. The obtained
DBPILs was dried at 50oC for 24 h under vacuum. DILA was synthesized by DBPILs and
79 | P a g e
aluminum hydroxide in a hydrothermal reactor. Amount of aluminum hydroxide and 2 eq.
of DBPILs were added into a flask. Then water was poured into the flask. The mixture
was stirred and heated at 100 oC for 24 hours under reflex condition. After the reaction,
the residue solid was removed by filtration, and the water was removed by reduced
pressure distillation. Finally, DILA was obtained by recrystallized using as acetonitrile as
a solvent.
4.2.3 Characterization
Fourier transform infrared (FT-IR) spectra were recorded on a Thermo Nicolet 380
spectrophotometer with anhydrous KBr as standard (Thermo Electron Co.). NMR spectra
were recorded on a Bruker AVANCE III HD 300 spectrometer with DMSO-d6 as solvent.
4.2.3.1 Characterization of the catalysts
DBPILs-a
Figure 4.2 1H NMR of DBPILs-a
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Figure 4.3 13C NMR of DBPILs-a
DILA
81 | P a g e
Figure 4.4 1H NMR of DILA
Figure 4.5 13C NMR of DILA
4.2.3.2 Characterization of the cyclic carbonates
Spectra of product 1H NMR and 13C NMR of Products
3a:
1H NMR ((CDCl3, TMS, 400 MHz): 3.84 (d, J = 6.0 Hz, 2H), 4.05 (t, J = 8.4 Hz, 1H),
4.60 (t, J = 8.0 Hz, 1H), 5.07–5.10 (m, 1H). 13C NMR (CDCl3, TMS, 100 MHz): 44.15,
70.46, 73.51, 154.94.
3b:
1H NMR ((CDCl3, TMS, 400 MHz): 3.84 (d, J = 6.0 Hz, 2H), 4.05 (t, J = 8.4 Hz, 1H),
4.60 (t, J = 8.0 Hz, 1H), 5.07–5.10 (m, 1H). 13C NMR (CDCl3, TMS, 100 MHz): 44.15,
70.46, 73.51, 154.95.
3c:
82 | P a g e
1H NMR (CDCl3, TMS, 400 MHz): 0.88 (t, J = 7.5 Hz, 1H), 1.32 (dq, J = 14.8, 7.4 Hz,
2H), 1.42 – 1.56 (m, 2H), 3.46 (t, J = 6.5 Hz, 2H), 3.56 (dd, J = 11.5, 4.2 Hz, 1H), 3.63
(dd, J = 11.5, 2.7 Hz, 1H), 4.25 (dd, J = 8.3, 5.9 Hz, 1H) 4.52 (t, 3J = 8.4 Hz, 1H), 4.91
(dddd, J = 8.6, 6.0, 4.1, 2.8 Hz, 1H), 13C NMR (CDCl3, TMS, 100 MHz): 13.55, 18.63,
31.06, 66.00, 69.52, 70.54, 75.48, 154.88.
3d:
1H NMR (CDCl3, TMS, 400 MHz): 3.63 (dd, J = 4.0, 11.2 Hz, 1H), 3.70 (dd, J = 4.0,
11.2 Hz, 1H), 4.02–4.11 (m, 2H), 4.41 (dd, J = 6.4, 8.0 Hz, 1H), 4.51 (dd, J = 8.4, 8.4 Hz,
1H), 4.79–4.85 (m, 1H), 5.22–5.32 (m, 2H), 5.83–5.93 (m, 1H); 13C NMR (100 MHz,
CDCl3) δ 65.9, 68.6, 72.0, 75.0, 117.1, 133.5, 154.8.
3e:
1H NMR (CDCl3, TMS, 400 MHz): 4.34 (t, 1H, J = 8.4 Hz); 4.80 (t, 1H, J = 8.4 Hz);
5.68 (t, 1H, J = 8.0 Hz); 7.35–7.44 (m, 5H); 13C NMR (CDCl3, TMS, 100 MHz): 71.10,
77.92, 125.81, 129.12, 129.63, 135.70, 154.81
3f:
1H NMR (CDCl3, TMS, 400 MHz): 2.13 (s, 3H), 4.18 (dd, J = 11.2, 3.5 Hz, 1H), 4.27
(dd, J = 11.2, 2.4 Hz, 1H), 4.47 (dd, 3J = 8.4 Hz, 5.2Hz, 1H), 4.64 (t, 3J = 8.5 Hz, 1H),
5.17 (m, 1H), 6.88 (td, J = 7.4, 0.8 Hz, 1H), 6.93 (d, J = 7.8 Hz, 1H), 7.14-7.17 (m, 2H).
13C NMR (CDCl3, TMS, 100 MHz): 15.49, 66.17, 68.84, 74.11, 114.57, 121.92, 129.62,
154.65
3g:
1H NMR (CDCl3, TMS, 400 MHz): 4.15 (dd, 3J = 4.4 Hz, 2J = 10.8 Hz, 1H), 4.24 [dd,
3J = 3.6 Hz, 2J = 10.8 Hz, 1H), 4.55 (dd, 3J = 8.4 Hz, 2J = 6 Hz, 1H), 4.62 (t, 3J = 8.4 Hz,
1H), 5.03 (m, 1H), 6.91 [d, 3J = 8.0 Hz, 2H), 7.08 (s, 1H), 7.31 (t, 3J = 8.0 Hz, 2H). 13C
NMR (CDCl3, TMS, 100 MHz): 66.17, 68.84, 74.11, 114.57, 121.92, 129.62, 154.65
3h:
83 | P a g e
1H NMR ((CDCl3, 400 MHz): 1.33-1.54 (m, 2H), 1.57-1.74 (m, 2H), 1.81-2.2 (m, 4H),
4.59 -4.77(m, 2H). 13C NMR (CDCl3, TMS, 100 MHz): 19.18, 26.81, 75.74, 155.45.
3h:
1H NMR (CDCl3, TMS, 400 MHz): 1.52 – 1.55 (m, 2H), 3.46 (t, J = 5.9 Hz, 2H), 3.55
(dd, J = 11.5, 4.2 Hz, 1H), 3.63 (dd, J = 11.5, 2.7 Hz, 1H), 4.25 (dd, J = 8.2 5.9 Hz, 1H)
4.52 (t, 3J = 8.4 Hz, 1H), 4.91 (dddd, J = 8.6, 5.9, 4.2, 2.8 Hz, 1H), 13C NMR (CDCl3,
TMS, 100 MHz): 25.60, 66.09, 69.51, 70.55, 75.50, 154.93.
4.2.4 Procedure of the cycloaddition reaction of CO2 with epoxide
The coupling reaction of carbon dioxide and epoxide was carried out in a 20 mL
Schlenk tube with a magnetic stirrer. In a typical reaction, 0.5ml of epoxides and chosen
amounts of catalyst were added into the reactor. Then, a balloon of CO2 was connected
to the schlenk tube, controlling the temperature within the desired range afterwards. After
the reaction, the remaining CO2 was vented out slowly. The yield of the products was
characterized by HNMR spectroscopy of the crude reaction mixture on a Bruker AVANCE
III HD 300 spectrometer by using CDCl3 as solvents.
4.2.5 Recycle experiment
After the reaction, 10 ml ethyl acetate was poured in to the schlenk tube, the ionic
liquids catalyst precipitated from the mixture, and then catalyst was separated from the
mixture by filtration and washed three times with ethyl acetate. Afterwards, the catalyst
was dried at 50 oC for 24 h in oven, and ready for the recycling experiment. The liquid
phase was dried at 80 oC by vacuum distillation, afterwards the product can be obtained.
The yield of the product was calculated by weight.
4.3 Results and discussion
4.3.1 Activities of various catalysts
It has been proven that Br- is an excellent nucleophilic ion for the cycloaddition
reaction in our previous work.[145,223] Br- is chosen as a model ion for this reaction. After
the catalysts were synthesized, their activities were investigated via the cycloaddition
84 | P a g e
reaction of epichlorohydrin with CO2 to synthesize chloropropene carbonate (CPC) in a
schlenk tube at 30 °C, and the corresponding results were displayed in Table 4.1. As a
raw material of DILA, Al(OH)3 and BrC2COOH showed no CPC produced in catalyzing
the reaction under this room temperature and 1bar CO2 condition (Entry 1, 2). The reason
maybe that Al(OH)3 cannot dissolved in epichlorohydrin and BrC2COOH cannot
dissociate Br-. TBAB was reported as a co-catalyst that widely used the cycloaddition
reaction of CO2 with epoxide, and it only exhibited a 19% yield of CPC at this mild
condition.
Table 4.1: Reactions of CO2 with epichlorohydrin catalyzed by different ILsa
Entry Catalyst Time (h) Yieldb (%) TOF (h-1)
1 Al(OH)3 6 trace ---
2 c BrC2COOH 6 trace ---
3 TBAB 6 19 0.5
4 DBPILs-a 6 73 2.0
5 DILA 6 94 2.7
6d DILA 2 60 7.5
aReaction conditions: epichlorohydrin (0.5ml), ILs (6 mol%), 1 bar of CO2 (balloon), Temperature
(30oC). bDetermined by 1H NMR spectroscopy of the crude reaction mixture. c BrC2COOH = 3-
bromopropionic acid, TBAB = Tetrabutylammonium bromide. d Catalyst (4 mol %), e Catalyst (25
mol %). TOF = turn over frequency = mol of CPC generated per mol catalyst and per hour.
For comparison purpose, DBPILs-a with a protic acid was synthesized and
investigated (entry 4). DBPILs-a showed a much higher yield of CPC (73%) than TBAB
(Entry 4 vs entry 3). Based on our previous work, the possible reason was that DBPILs-
a had a strong H-bond interaction with epoxide, which made the ring open of
epichlorohydrin much easier. Then, DILA was prepared and used for this reaction at the
same conditions, and it displayed a 94% yield of CPC within 6 hours (Entry 7), the highest
CPC yields of all the catalysts at room temperature and 1bar CO2 pressure. To our
surprise, when we reduce the reaction time to 2 hours and the dose of catalyst to 4%, the
catalyst DILA showed a 60% yield of CPC with a TOF of 7.5 (Entry 6). The high activity
maybe caused by the activation of epoxides by the powerful aluminum ion and
nucleophilic bromide ion.
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4.3.2 Effect of reaction conditions
Figure 4.6 Effects of reaction time under different temperature. Reaction conditions:
epichlorohydrin (0.5 ml), catalyst dose (4%), 1 bar CO2 (balloon).
The effect of reaction time was investigated with different temperature under a
catalyst dose of 4% and 1 bar of CO2 (Figure 4.6). It could be obviously seen that the
CPC yield increased with the increasing of reaction time and temperature. It displayed
83%, 91% and 99% yields of CPC within 6 hours at 25 oC, 30 oC and 50 oC separately.
In the initial of the reaction, the yield of CPC is almost linear. However, the reaction rate
will decrease with the increasing of CPC, and the yield of CPC goes to a slow growth
stage. The possible reason maybe that the producing of CPC result in the viscosity of
reaction system increased, which affect the transferring effect of CO2 in the liquid phase.
Considered that the yield of CPC is almost liner in initial of the 2 hours at 25 oC and 30oC,
2 hours are chosen as the best time for the next studies.
The effect of catalyst dose on the reaction was investigated under the 30oC and
balloon of CO2 within 2 hours (Figure 4.7). It could be seen that the catalyst amount
showed great effect on CPC yield. The increase of catalyst dose resulted in an obviously
increase in CPC yield under a catalyst amount level of 1% - 5%. But the further increasing
amount of catalyst exhibited negative influence on CPC yield (1% - 5%). It could be
explained that, when catalyst dose is higher than 5%, the viscosity of reaction system will
increase quickly with the increasing of DILA at this room temperature, and result in the
0 1 2 3 4 5 6
20
40
60
80
100
Yie
ld (
%)
Time (h)
25 oC
30 oC
50 oC
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negative effect of transferring CO2 in liquid phase. The results indicated that adopting
appropriate catalyst dose had significant impact on the cycloaddition reactions. Therefor,
5% was chosen as the optimal catalyst loading for the next study.
Figure 4.7 Effects of catalyst dose. Reaction conditions: epichlorohydrin (0.5ml), 1 bar CO2
(balloon), temperature (30oC), reaction time (2 h).
Figure 4.8 Effects of temperature. Reaction conditions: epichlorohydrin (0.5ml), CO2 (balloon),
catalyst dose (5%), time (2 h).
0 1 2 3 4 5 6 70
20
40
60
80
Catalyst dose (%)
Yie
ld (
%)
25 30 35 40 45 50
40
50
60
70
80
90
100
Yie
ld (
%)
Temperature (oC)
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The effect of reaction temperature on the cycloaddition reaction was investigated
under 30oC and 1 bar of CO2 within 2 hours. As shown in Figure 4.8, the yield of CPC
increased linearly when temperature went up. DILA exhibited a good CPC yield within 2
hours (58%) even at 25oC. When temperature increased to 50oC, DILA showed a 90%
yield of CPC at 1 bar CO2 within 2 hours, which was promising in the industrial application.
4.3.3 Catalytic activity to various epoxides
Subsequently, a range of different substituted terminal epoxides were examined
under 1 bar of CO2 in the presence of DILA within 5 hours. Taking into account of the
industrial application, the reaction temperature was chosen as 50oC for the study. The
isolated yields of the target cyclic carbonates were determined by 1H NMR of the crude
reaction mixture. The result was exhibited in Table 4.2. In general, all of the terminal
epoxides showed excellent yields of corresponding carbonates (> 95%) under this mild
condition except the carbonate 3h. Only 72% yield of 3h obtained after 5 hours reaction.
This may be caused by the high stereo-hindrance effect.
Table 4.2: Reaction of CO2 with substrates catalyzed by DILAa
3a: 99% 3b: 99% 3c:95%
3d: 99% 3e: 95% 3f: 97%
3g: 96% 3h: 72%
aYield were determined by HNMR of the crude reaction mixture.
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4.3.4 Recycling of the catalyst
Figure 4.9 Recycle experiment catalyzed by DILA. aReaction conditions: 2g (0.5ml), DILA (5
mol%), 1 bar of CO2 (99.995%, balloon), temperature (50oC), reaction time (5 h).
Recycle experiments were also conducted to examine the stability of the catalyst
DILA for the fixation of CO2 with epoxides. 2f was chosen as an optimal terminal epoxide
to study the cycling performance of DILA for the easy separation by adding ethyl acetate.
The results displayed in Figure 4.9 showed that the catalyst DILA could be reused for at
least 4 runs without any obviously decrease of catalytic activity.
4.3.5 Probable mechanism
Based on the previous reports and the results above, we proposed a possible
mechanism for chemical fixation reaction of CO2 into cyclic carbonate catalyzed by
catalyst DILA (Scheme 4.2). Firstly, aluminium ion of DILA can activate epoxide and make
the C-O bond of epoxide polarized, which led to the ring opening of epoxide easier. Then,
the nucleophilic attack of Br- on less sterically hindered carbon atom of the epoxide
caused the ring opened and transforms into intermediate B. Subsequently, the negative
ions of oxygen of the catalyst coordinated with CO2 to form complex C. Nucleophilic attack
of O- on the carbamate salt produced the alkyl carbonate D. Finally, the cyclic carbonate
is obtained by ring-closure step and the catalyst DILA is regenerated.
1 2 3 4
0
20
40
60
80
100
Yie
ld (
%)
Run times
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Scheme 4.2. Probable mechanism of the cycloaddition reaction catalyzed by DILA.
4.4 Conclusions:
In summary, a powerful DILA with nucleophilic site and aluminum ion was
synthesized and successfully used as a single-component catalyst in the cycloaddition
reaction of CO2 with epoxides at 1 bar CO2 and very mild temperature (25-50oC). It
showed excellent activity under this mild condition and was found to be applicable to
various epoxides. Furthermore, the catalyst could be reused at least four times without
any obviously decrease of catalytic activity. A possible mechanism of ring-opening of
epoxide assisted by aluminum ion and activation of CO2 induced by negative ions of
oxygen was proposed. This work provides a highly efficient and recycling aluminum
containing ionic liquids for conversion of CO2 with epoxide at very mild condition, which
is promising for the applications of CO2 conversion.
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Chapter 5: Poly Ionic Liquids Based Membranes as Highly
Efficient Heterogeneous Catalyst for Conversion of CO2 to
Cyclic Carbonate under Mild Conditions
5.1 Introduction
The combination of high activity and easy recovery of catalysts is recognized as a
great challenge in catalysis research from an industrial point of view.[237] The reported
homogeneous catalysts are usually more efficient, while it is costly to reclaim them from
reaction products. By contrast, heterogeneous catalysts can be easily separated from the
products and reused. But they are inefficient, and at the same time, high temperatures
and pressures are often demanded, which make them expensive. This has promoted the
development of efficient strategies for homogeneous catalysis and heterogeneous
separation.[175,176]
The efficient conversion of CO2 with epoxide to produce cyclic carbonate at mild
conditions still remains an important issue. To this end, various catalysts have been
developed for the synthesis of cyclic carbonates under mild conditions of ambient CO2
pressure and/or room temperature. In the respect, we also synthesized a series of well-
designed ionic liquids and used as highly efficient homogenous catalyst for this reaction
in our previous works. Although the ionic liquids catalyst showed excellent yields of cyclic
carbonate at room temperature and 1 bar CO2, which made this reaction promising
energy saving process. The separation of ionic liquids catalyst and cyclic carbonate is
inconvenient, and distillation process is always needed, which led to the increasing of the
energy input. On the basis of the problems in homogeneous catalytic processes, some
heterogeneous catalysts have been developed for chemical conversion of CO2 to cyclic
carbonates under mild conditions. In contrast, heterogeneous systems are easier to
separate, but they are inefficient and long reaction time, large amount loading of catalyst
and co-catalyst hard reaction conditions are always needed. Hence, it is highly necessary
to explore a convenient approach to realize both high activity and quick separation of
catalysts.
Recently, Gao group[238] reported a kind of cross-linked poly(ionic liquid)s (PILs)
with swelling property to increase catalytic activities of heterogeneous catalysts. The
swelling property could promote the contact of nonporous PILs with substrates. The
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swelling PILs were successfully utilized for the reaction of 2-(arylamino) ethanol and
ethylene carbonate (EC), and showed excellent catalytic activities, which was similar to
homogeneous ionic liquid monomers. Gao group[239] synthesized another PILs by
polymerization of N-vinylimidazolium with divinylbenzene (DVB) and they were utilized in
the reaction of 2-(phenylamino) ethanol (2-PAE) and EC. It was found that the PILs
exhibited even better catalytic performance than homogeneous catalyst 1-butyl-3-methyl-
imidazolium acetate (BmimOAc) because of the swelling property and selective
absorption.
In spired by this, we synthesized a series of cross-linked poly (vinylimidazole/butyl
acrylate) ionic liquids membranes (PVBILs). The PVBILs were successfully used as a
heterogeneous catalyst in the cycloaddition reaction of CO2 with epoxide to produce cyclic
carbonate under mild conditions. The best PVBILs showed a 90 % yield of chloropropene
carbonate (CPC) in 24 hours with a catalyst loading of 2 % at 50 oC and 1 bar of CO2.
The high activity was even better than homogenous catalyst, because of the good
swelling property and CO2 solubility of PVBILs. The using of cross-linked PVBILs
membranes for the cycloaddition reaction of CO2 with epoxide to produce cyclic
carbonate supply an efficient way to combine activity and recovery of catalysts, which is
benefit for energy-saving and industrial applications.
5.2 Experimental section
5.2.1 General information
Carbon dioxide was supplied by Air Liquide Danmark with a purity of 99.995%.
Chemicals and solvents such as butyl acrylate, N-vinylimidazole, azodiisobutyronitrile
(AIBN), dimethylformamide (DMF), CDCl3, 1, 6-dibromohexane, 1-bromobutane, 1-
bromoethanol and all of the epoxides unless otherwise specified were bought from
Sigma-Aldrich and were used without further purification.
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5.2.2 Synthesis of catalyst used in this study.
5.2.2.1 Preparing of PVBILs
Scheme 5.1 Two step for the synthesis of PVBILs (Step 1 synthesis of copolymers)
The PVBILs were prepared by two step method based on the report. [240] Here,
copolymers poly (Vim/BuA n:m = 1:1) was chosen to show the synthetic process (Scheme
5.1). In a typical reaction, 0.53 mmol of AIBN was dissolved in DMF (10 mL) in a 100 ml
flask, and then monomers 1-vinylimidazole (20 mmol) and butyl acrylate (20 mmol) were
added into the flask. After remove all traces of air by bubbling nitrogen for 20 min, the
mixture was stirred for 10 h at 70°C under nitrogen conditions. When the reaction was
finished, the crude product could be precipitated by adding of ether, and then purified by
recrystallization method using EtOH as a solvent. Finally, the obtained product was dried
in vacuum oven for 24 hours. Other copolymers were synthesized in the same way by
changing the ratio of VIm-co-BuA.
Scheme 5.2 Two step for the synthesis of PVBILs (Step 2)
After copolymers were obtained, PVBILs were prepared based on reported
literature.[240] Here, PVBILs 1h was chosen to show the synthetic process (Scheme 5.2).
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In a typical reaction, the obtained copolymer poly (VIm-co-BuA n:m = 3:7) (1.5 g, n=3.0
mmol) was dissolved in ethanol (12 mL) by stirring overnight. Then, 1,6-dibromohexane
(0.12 g, 0.5 mmol) and 1-bromobutane (0.13 g, 1 mmol) were added in to the mixture.
The mixture solution was degassed by ultrasonication for 10 min and solvent-casted in a
Teflon petri dish. Put the casting solution to remove entrapped residues of solvent at room
temperature. The cast membrane was dried in vacuum oven for 12 hours at 65 oC. Finally,
the obtained PVBILs membranes were ground into small particles in liquid nitrogen for
using. Other PVBILs were synthesized in the same way by changing the ratio of the
reactant.
5.2.2.2 Preparing of Poly [VBIM][Br] (PVIMBr)
Scheme 5.3 Synthesis of PVIMBr by two steps
PVIMBr was synthesized by two-step method based on the reported literature[144]
(Scheme 5.3). In a typical reaction, 1-vinylimiazole (5 g, 53 mmol) and AIBN (0.087 g,
0.53 mmol) were dissolved in DMF (10 mL), the reaction was conducted at 80 oC under
the protection of nitrogen. After 12 hours reaction, the mixture was cool to room
temperature. A brown solid poly (VIm) was obtained by adding of acetone. Wash product
three times by acetone. Then poly (VIm) (0.25 g, 2.6 mmol) and 1-bromobutane (0.64 g,
2.6 mmol) were dissolved in ethanol (12 mL), and casting the solution in a small Teflon
petri dish (5*5 cm). Put the casting solution to remove entrapped residues of solvent at
room temperature. The cast membrane was dried in vacuum oven for 12 hours at 70 oC.
Finally, the obtained PVIMBr were ground into small particles in liquid nitrogen for using.
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5.2.2.3 Preparing of Poly(butyl acrylate) (PBA)
Scheme 5.4 Synthesis of PBA
PBA was prepared in accordance with the general polymerisation procedure
(Scheme 5.4). In a typical reaction, butyl acrylate (5.12 g, 40 mmol) and AIBN (0.087 g,
0.53 mmol) were dissolved in DMF (10 mL). The product polymer was reclaimed as a
transparent liquid with high viscosity after precipitation into DI water.
5.2.3 Characterization
Fourier transform infrared (FT-IR) spectra were recorded on a Thermo Nicolet 380
spectrophotometer with anhydrous KBr as standard (Thermo Electron Co.). NMR spectra
were recorded on a Bruker AVANCE III HD 300 spectrometer with DMSO-d6 as solvent.
5.2.3.1 Characterization of the catalysts
Poly(vinylimidazole)
Yield > 65%. Tg=164.2°C. IR (cm-1): 3111cm-1 (C=C-H stretching), 1660 cm-1 (C=N
stretching), 1494 cm-1 (N=C-H stretching), 1282 cm-1 and 1230 cm-1 (ring vibrations), 914
cm-1 (C-H out of plane bending), 662 cm-1 (ring torsion), 634 cm-1 (C=C-H and N=C-H
wagging). 1H-NMR (1H, ppm, DMSO-d): 7.49-6.62 (m, 3H), 3.24-2.78 (m, 1H), 1.96 (s,
2H)
PVIMBr
Yield > 65%, Tg= 164.2 oC. IR (cm-1): 3111cm-1 (C=C-H stretching), 1660 cm-1 (C=N
stretching), 1494 cm-1 (N=C-H stretching), 1282 cm-1 and 1230cm-1 (ring vibrations), 914
cm-1 (C-H out of plane bending), 662 cm-1 (ring torsion), 634 cm-1 (C=C-H and N=C-H
wagging). 1H-NMR ( H, ppm, DMSO-d): 7.49-6.62 (m, 3H), 3.24-2.78 (m, 1H), 1.96 (s,
2H)
95 | P a g e
PBA
Yield > 65%, Tg= -47.4oC. IR (cm-1): 3011-2827 cm-1, 1451cm-1 and 1381cm-1 (-CH2-
symmetric and asymmetric stretching), 1727 cm-1and 1154 cm-1 (stretching vibration C=O
and C-O-C in acrylate group). 1H-NMR ( H, ppm, CDCl3): 3.96 (m, 2H), 2.39-1.44 (m, 3H),
1.56 (m, 2H), 1.31 (m, 2H) 0.87(m, 3H).
Poly(Vim/BuA n:m = 1:1)
IR (cm-1): 3111cm-1 (C=C-H), 3012-2844 cm-1, 1451cm-1 (-CH2-), 1727 cm-1 and
1160 cm-1 (C=O and C-O-C in acrylate group), 1494 cm-1 (N=C-H), 1267 cm-1 and
1223cm-1 (ring), 912 cm-1 (C-H), 664 cm-1 (ring), 632 cm-1 (C=C-H and N=C-H); 1H-NMR
(1H, ppm, CDCl3): 7.4-6.4 (m, 3H), 4.1-3.5 (m, 2H), 2.27-1.45(m, 6H), 1.46 (m, 2H), 1.26
(m, 2H), 0.87 (m, 3H).
Poly (Vim/BuA n:m = 3:7)
IR (cm-1): 3111cm-1 (C=C-H stretching), 3012-2844 cm-1, 1451cm-1 (-CH2- symmetric
and asymmetric stretching), 1722 cm-1and 1160 cm-1 (stretching vibration C=O and C-O-
C in acrylate group), 1494 cm-1 (N=C-H stretching), 1267 cm-1 and 1223cm-1 (ring
vibrations), 912 cm-1 (C-H out of plane bending), 664 cm-1 (ring torsion), 632 cm-1 (C=C-
H and N=C-H wagging); 1H-NMR (ppm, CDCl3): 7.4-6.4 (m, 3H), 3.96 (m, 2H), 2.35-1.62
(m, 6H), 1.52 (m, 2H), 1.27 (m, 2H) 0.86(m, 3H).
Poly (Vim/BuA n:m = 7:3)
IR(cm-1): 3112cm-1 (C=C-H stretching), 3012-2800 cm-1, 1455cm-1 (-CH2- symmetric
and asymmetric stretching), 1722 cm-1and 1164 cm-1 (stretching vibration C=O and C-O-
C in acrylate group). 1663 cm-1 (C=N stretching), 1494 cm-1 (N=C-H stretching), 1275 cm-
1 and 1227cm-1 (ring vibrations), 912 cm-1 (C-H out of plane bending), 664 cm-1 (ring
torsion), 636 cm-1 (C=C-H and N=C-H wagging); 1H-NMR ( ppm, DMSO-d): 7.52-6.62 (m,
3H), 4.05-3.55 (m, 2H), 2.27-1.45(m, 6H), 1.45 (m, 2H), 1.24 (m, 2H) 0.87(m, 3H).
5.2.3.2 Characterization of the cyclic carbonates
Spectra of product 1H NMR and 13C NMR of Products
1H NMR ((CDCl3, TMS, 400 MHz): 3.84 (d, J = 6.0 Hz, 2H), 4.05 (t, J = 8.4 Hz, 1H),
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4.60 (t, J = 8.0 Hz, 1H), 5.07–5.10 (m, 1H). 13C NMR (CDCl3, TMS, 100 MHz): 44.15,
70.46, 73.51, 154.94.
1H NMR (CDCl3, TMS, 400 MHz): 4.15 (dd, 3J = 4.4 Hz, 2J = 10.8 Hz, 1H), 4.24 [dd,
3J = 3.6 Hz, 2J = 10.8 Hz, 1H), 4.55 (dd, 3J = 8.4 Hz, 2J = 6 Hz, 1H), 4.62 (t, 3J = 8.4 Hz,
1H), 5.03 (m, 1H), 6.91 [d, 3J = 8.0 Hz, 2H), 7.08 (s, 1H), 7.31 (t, 3J = 8.0 Hz, 2H). 13C
NMR (CDCl3, TMS, 100 MHz): 66.17, 68.84, 74.11, 114.57, 121.92, 129.62, 154.65
5.2.4 Procedure of the cycloaddition reaction of CO2 with epoxide
The coupling reaction of carbon dioxide and epoxide was carried out in a 20 mL
Schlenk tube with a magnetic stirrer. In a typical reaction, 0.5ml of epoxides and chosen
amounts of catalyst were added into the reactor. Then, a balloon of CO2 was connected
to the schlenk tube, control the temperature within the desired range afterwards. After the
reaction, the remaining CO2 was vented out slowly. The yield of the products was
characterized by HNMR spectroscopy of the crude reaction mixture on a Bruker AVANCE
III HD 300 spectrometer by using CDCl3 as solvents.
5.2.5 Swelling ratio measurement
The swelling property was evaluated by calculating the swelling ratio. First, record
the weights of dry membranes by an electronic balance. Then catalyst membrane used
in this study was immersed in the ethanol until the weight was constant. Finally calculate
the swelling ratio by following equation. Swelling ratio = (Ww - Wd) /Wd
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5.3 Results and discussion
5.3.1 Activities of various catalysts
Figure 5.1 Catalyst used in this study.
The structures of the catalysts used in this study were displayed in Figure 5.1. After
the catalysts were synthesized, the swelling ratio of the catalyst used in this study was
tested first by using ethanol as a solvent instead of epoxide, because of the toxic of the
epoxide. Their activities were also investigated via the cycloaddition reaction of
epichlorohydrin with CO2 to synthesize chloropropene carbonate (CPC) in a schlenk tube
at 50 °C. The corresponding results were showed in Table 5.1.
It has been proven that Br- is an excellent nucleophilic ion for the cycloaddition
reaction in our previous work.[145,223] Herein, catalyst loading is based on per unit of
bromide. As shown in Table 1, both PBA and PVIMBr had no swelling ability. PBA had
no catalytic activity at this mild condition (Entry 1), because it has no nucleophilic bromide
ion to activate epoxide. PVIMBr was reported an efficient heterogeneous catalyst for
cycloaddition reaction of CO2 and epoxide at 130 oC and 2 MPa CO2 pressure. However,
it only showed 2 % yield of CPC with 12 hours reaction under 50 oC and 1 bar CO2 (Entry
2).
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Table 5.1 Catalyst screening for conversion of CO2 to CPC
Entry Catalyst Swelling (wt%) Yieldb (%)
1 PBA ---- 0
2 PVIMBr ---- 2
3 1a 48 19
4 1b 58 39
5 1c 66 52
6 1d 123 68
7 1e 120 54
8 1f 162 76
9c 1f 162 90
aReaction conditions: epichlorohydrin (1 ml), catalyst (2 mol%), 1 bar of CO2 (balloon), Temperature
(50 oC), Time (12 h). bDetermined by 1H NMR spectroscopy using CDCl3 as a solvent. cTime (24 h).
To our surprise, PVBILs 1a with a swelling ratio of 48 % showed a 19 % yield of CPC
at the same conditions (Entry 3). When compared the PVBILs that with same groups but
different swelling ratio, we found the ratio of vinylimidazole (VIM) and butyl acrylate (BA)
could affect the swelling ability. The order of swelling ratio is 1c >1b>1a (Entry 5 vs 4 and
3), which indicate that the swelling ability ratio increase with the decreasing of the ratio of
VIM:BA. Furthermore, the catalytic activity was well consistent with the swelling ability,
and 1c showed highest activity of these three catalysts, 52 % yield of CPC could be
obtained in 12 hours. The same behaviour was also found in the other PVBILs catalysts
used in this study. However, 1d displayed much higher activity than 1e, even they had a
similar swelling ratio (Entry 6 vs 7). The possible reason maybe that 1d had imidazole
groups, which can activate CO2 efficiently and led to the high activity. Based on our
previous work, the hydroxyl group could activate epoxide through hydrogen-bond
interaction with epoxide and made the ring open of epichlorohydrin much easier.
Therefore, PVBILs 1f containing hydroxyl groups and imidazole groups was prepared and
used for this reaction at the same conditions. PVBILs 1f showed the highest yield of CPC
and swelling ability among all the catalysts (Entry 8 vs 1-7), because of the activation of
CO2 and epoxide by imidazole groups and hydroxyl groups. When we increased the
reaction time to 24 hours, the PVBILs 1f showed a 90 % yield of CPC at the same
conditions. Then 1f was chosen as a best catalyst for the next studies.
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5.3.2 Effect of reaction conditions
0.5 1.0 1.5 2.0 2.5 3.0
0
20
40
60
80
Yie
ld (
%)
Catalyst dose (mol%)
Figure 5.2 Effects of catalyst loading (Epichlorohydrin:1 ml, 1 bar CO2, Temperature: 50°C,
Time: 12 h).
The effect of catalyst loading on the reaction was investigated under the 30oC and
balloon of CO2 within 12 hours (Figure 5.2). It could be seen that the catalyst amount
showed great effect on CPC yield. The increase of catalyst loading resulted in an
obviously increase in CPC yield under a catalyst amount level of 0.5 % - 2 %. But the
further increasing amount of catalyst exhibited negative influence on CPC yield (2% - 3%).
It is easy to understand the CPC yield increased with the increasing of catalyst loading at
catalyst amount level of 0.5 % - 2 %. And the decreasing part can be explained that,
epichlorohydrin will swelled in PVBILs during the reaction, because the amount of
epichlorohydrin is fixed, therefore the concentration of epichlorohydrin per Br- of the
PVBILs decreased with the increasing catalyst dose, which will reduce the interaction
between the epoxides and the activate site from PVBILs, and finally resulted in the
decreasing of catalytic activity. Too high catalyst loading did not benefit the cycloaddition
reaction catalyzed by PVBILs and adopting appropriate catalyst dose had significant
impact on the cycloaddition reactions. Therefore, the catalyst loading of 2 % was chosen
for the optimal catalyst dose for next study.
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0 3 6 9 12 15 18 21 24 27 30
0
20
40
60
80
100
Yie
ld (
%)
Time (h)
Figure 5.3 Effects of reaction time (Epichlorohydrin: 1 ml, 1 bar CO2, Temperature: 50°C,
Catalyst: 2 mol% per bromide unit).
The effect of reaction time was investigated with different temperature under a
catalyst dose of 2 % and 1 bar of CO2 (Figure 5.3). It could be obviously seen that the
CPC yield increased with the increasing of reaction time. In the initial of the reaction, the
yield of CPC is almost linear and reached to 82 % within 12 hours. However, the reaction
rate will decrease with the increasing of CPC, and the yield of CPC goes to a slow growth
stage. The possible reason maybe that CPC can not get out from PVBILs 1f during the
reaction, the producing of CPC will occupy a lot of reaction area, which will reduce the
interaction between epoxides and the activate sites of PVBILs, and finally resulted in the
decreasing of reaction rate. Considered that the yield of CPC is almost liner in initial of
the 9 hours at 30oC, 9 hours are chosen as the best time for the next studies.
5.3.3 Catalytic activity to various epoxides
Scheme 5.5. Reaction of CO2 with substrates catalyzed by 1f
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Subsequently, different substituted terminal epoxide glycidyl phenyl (EGP) ether was
examined under 1 bar of CO2 and 50 oC in the presence of 1f. The isolated yields of the
target cyclic carbonates were determined by 1H NMR of the crude reaction mixture.
However, 1f only showed a 28 % yield of corresponding cyclic carbonate after 25 hours
reaction at this mild condition (Scheme 5.5). The possible reason maybe that, the swelling
ability of 1f for EGP is low because of the big molecular structure of EGP compared to
epichlorohydrin, based on the above study, the low swelling ability can reduce the
catalytic activity sharply.
5.3.4 Recycling of the catalyst
Figure 5.4 Photograph shows the different of catalyst 1f before and after reaction
Recycle experiments were conducted to examine the stability of the catalyst 1f for
the fixation of CO2 with epichlorohydrin to produce CPC. After the reaction, catalyst 1f
could be recovered by adding of ethanol and filtration. However, the yield of CPC
decreased from 76% to 52% after 2 runs, and the colour of the catalyst changed from
white and transparent to canary yellow (Figure 5.4). The decreased yield of CPC maybe
caused by the side-reaction. Another reason maybe that, there are still some CPC or
epichlorohydrin left in the recovered 1f because of the swelling, which will reduce the
swelling ability of 1f and result in the decreasing catalytic activity of 1f. Further studies
will be focus on the characterisation of recovered catalyst 1f to find the mechanism of the
decreasing catalytic activity during the recycling experiment.
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5.3.5 Probable mechanism
Scheme 5.6 Probable mechanism of the cycloaddition reaction catalyzed by DILA.
Based on the previous reports and the results above, we proposed a possible
mechanism for chemical fixation reaction of CO2 into cyclic carbonate catalyzed by
catalyst 1f (Scheme 5.6). Firstly, hydroxyl group of 1f can activate epoxide and make the
C-O bond of epoxide polarized, which led to the ring opening of epoxide easier. Then, the
nucleophilic attack of Br- on less sterically hindered carbon atom of the epoxide caused
the ring opened and transforms into intermediate B. Subsequently, the imidazole nitrogen
of the catalyst coordinated with CO2 to form complex C. Nucleophilic attack of O- on the
carbamate salt produced the alkyl carbonate D. Finally, the cyclic carbonate is obtained
by ring-closure step and the catalyst 1f is regenerated.
5.4 Conclusions
In summary, a series of cross-linked poly (vinylimidazole/butyl acrylate) ionic liquids
membranes (PVBILs) were prepared and used as highly efficient heterogeneous
catalysts for fixation of CO2 with epoxide at mild conditions. PVBILs could show
comparable activities in the coupling of epoxide and CO2 with the traditional homogenous
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catalysts, because of the activity of CO2 and “homogeneous-surroundings” caused by
swellable properties. Swelling behaviour was studied and found to be consistent with the
experimental results of the catalytic activity. The dependence of conversion yield on
catalyst dose, reaction temperature and time were investigated. The best PVBILs could
show a 90% yield of carbonate within 24 hours at 50 oC and 1 bar of CO2. This work
provides a highly efficient way to combine the advantage of homogeneous catalyst and
heterogeneous catalyst, which is promising for the applications of CO2 conversion.
Note:
This part of work was cooperated with Ting Song. The synthesis, characterization of
the catalyst and the swelling experiment were done by Ting Song.
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Chapter 6: Biological Porphyrin Ionic Liquids as
Photocatalysts for Conversion of CO2 to Carbonates
6.1 Introduction
Carbon dioxide, well known as a global warming gas, is also regarded as an
abundant, nontoxic and renewable C1 resource. The utilization of CO2 as raw materials
for production of energy carriers and chemicals has been widely demonstrated. One of
the typical feasible routes is the synthesis of five-membered cyclic carbonates by
cycloaddition of CO2 with epoxides.
A large range of catalytic systems have been reported for the cycloaddition of
carbon dioxide to produce cyclic carbonates. Specially, ionic liquids (ILs) have obtained
much attention as both green solvent and catalyst for this reaction because its high
capability for CO2 capture and easy tuning basicity-nucleophilicity by simple design of the
IL structure. Although most of the ionic liquid catalyst systems show a good yield to
produce carbonates, high temperatures and high CO2 pressures are always needed,
which makes this process not so “sustainable”. Therefore, co-catalysts containing metal
ions are widely used to improve the catalytic performance of ILs under mild conditions.
Among all of the metal containing co-catalyst metalloporphyrins have received much
interest due to the unique framework structure of porphyrin. For example, Xiao and Meng
et al[153] reported a porphyrin based porous organic polymer (POP-TPP) for this
cycloaddition reaction of CO2. The catalytic activities of metalloporphyrins can be easily
adjusted by introducing different metal ions such as Co3+, Zn2+, and Mg2+. As
heterogeneous catalysts, these meatal based POP-TPP were very active for this reaction
at ambient conditions with the presence of TBAB. Diphenylporphyrin]manganese(III)
chloride / phenyltrimethylammonium tribromide [152] and bisimidazole-functionalized
porphyrin cobalt(III) complexes[154] were also reported for the cycloaddition of CO2 to
produce cyclic carbonate under mild conditions.
Most recently (In the year 2019), Jiang et al.[150] first reported the integration of
photothermal effect of carbon-based Zn-MIF materials for the cycloaddition of CO2 with
epoxide. The best catalyst showed 94 % yield of cyclic carbonate after 10 hours with the
presence of TBAB as co-catalyst and DMF as solvent under 1 bar CO2, 300 mW·cm-2
full-spectrum irradiation and ambient temperature. This work is the first report on
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integration of photothermal effect for the cycloaddition of CO2 with epoxide to produce
cyclic carbonate. As a biomimetic catalyst, metalloporphyrin could not only activate CO2
at atmospheric CO2 conditions, but also have a good capacity of visible light absorption.
Figure 6.1. Picture shows the synthesis of carbonates catalysed by bio-porphyrin ionic liquids
Inspired by these works, we designed a series of biological metalloporphyrin based
ionic liquids (MPIL) to combine the advantages of ionic liquid and metalloporphyrin
(Figure 6.1). These MPIL catalysts can activate the epoxide and make the key step much
easy. The activation of CO2 supported by the ionic liquid part and metal centre of
porphyrin helps to react with epoxide at atmospheric CO2 conditions. Furthermore, MPIL
have a good capacity of visible light absorption, thus can reduce the energy inputs greatly
by using the visible light and realize the efficient conversion of atmospheric CO2 to
carbonate at very mind conditions with a visible light.
6.2 General information
Carbon dioxide was supplied by Air Liquide Danmark with a purity of 99.995%.
Chemicals such as Zinc 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (90%),
5,10,15,20-Tetra(4-pyridyl)-21H, 23H-porphine (97%), 1,2-Epoxy-3-phenoxypropane
(99%) 3-Bromopropionic acid (97%) and all solvents unless otherwise specified were
bought from Sigma-Aldrich and were used without further purification. Photochemical
visible-light lamp source TOP-X500 was purchased from TOPTION INSTRUMENT CO.,
LTD China.
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6.3 Experimental section
6.3.1 Synthesis of catalysts
Scheme 6.1 One step synthesis of catalysts in this study.
Figure 6.2 [ZnTPPPA]+Br- precipitated from the solvents
Porphyrin-based ionic liquids catalysts were synthesized by one-step method.
[ZnTPPPA]+Br- was chosen as a model to show the process. In a typical reaction, Zinc
5,10,15,20-tetra(4-pyridyl)-21H, 23H-porphine (1.00 mmol) and 3-Bromopropionic acid
(6.00 mmol) were dissolved in 10 ml N,N-Dimethylformamide (DMF) in a 100 ml flask.
The mixture was heated and stirred for 24 hours at 120 oC. After the reaction, the mixture
was separated by filtration, then 50 ml of ethyl acetate was added to the liquid phase,
then [ZnTPPPA]+Br- precipitated from the solvents (see Figure 6.2). The crude
[ZnTPPPA]+Br- could be obtained by centrifugal separation method. Washed it three times
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with ethyl acetate, and dry it at 60 oC for 24 h under vacuum. Finally, a green colour
powder product was obtained.
6.3.2 Characterization of the catalysts
The morphology was observed through a scanning electron microscope (JEOL JSM
6700F). Fourier transform infrared (FT-IR) spectra were recorded on a Thermo Nicolet
380 spectrophotometer with anhydrous KBr as standard (Thermo Electron Co.). NMR
spectra were recorded on a Bruker AVANCE III HD 600 spectrometer with DMSO-d6 as
solvent.
6.3.3 Procedure of the cycloaddition reaction of CO2 with epoxide
Figure 6.3 Photographic image shows visible light equipment for the reaction
The procedure of the cycloaddition reaction of CO2 with epoxide with a visible light
was shown in Figure 6.3. The coupling reaction of carbon dioxide and epoxide was carried
out in a 100 mL photocatalytic reactor with a magnetic stirrer. In a typical reaction, 1 g of
epoxide and appropriate amounts of catalyst were charged into the reactor at room
temperature. Then, a balloon of CO2 was connected to the reactor. Control the spectrum
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irradiation within the desired range afterwards. After the reaction, the remaining CO2 was
vented out slowly, 10 ml ethyl acetate was added to the mixture, the liquid phase was
separated from catalyst by centrifugal method, then remove ethyl acetate by reduced
pressure distillation. After10 ml of water was added, products would precipitate from the
solvents, and then dried at 60 oC for 24 h under vacuum. The yield of the products was
characterized by weighing method.
6.3.4 Characterization of the catalysts and cyclic carbonates
Characterization of the catalysts
[ZnTPPPA]+Br-
Figure 6.4 1H NMR of [ZnTPPPA]+Br-
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Figure 6.5 SEM of the [ZnTPPPA]+Br-
Figure 6.6 UV spectrum of the [ZnTPPPA]+Br-
Spectra of product 1H NMR and 13C NMR of Products:
1H NMR (CDCl3, TMS, 400 MHz): 4.15 (dd, 3J = 4.4 Hz, 2J = 10.8 Hz, 1H), 4.24 [dd,
3J = 3.6 Hz, 2J = 10.8 Hz, 1H), 4.55 (dd, 3J = 8.4 Hz, 2J = 6 Hz, 1H), 4.62 (t, 3J = 8.4 Hz,
1H), 5.03 (m, 1H), 6.91 [d, 3J = 8.0 Hz, 2H), 7.08 (s, 1H), 7.31 (t, 3J = 8.0 Hz, 2H). 13C
NMR (CDCl3, TMS, 100 MHz): 66.17, 68.84, 74.11, 114.57, 121.92, 129.62, 154.65
200 300 400 500 600
Ab
sorb
an
ce (
a.u
)
(nm)
110 | P a g e
6.4 Results and discussion
Figure 6.7 Strctures of catalyst used in this study
We have been proved that Br- is an excellent nucleophilic ion for the cycloaddition
reaction in our previous work. Hence, Br- is chosen as the model anion. At the initial of
our study, we prepared a series of catalysts by one step method. The structure was
shown in Figure 6.7. The surface appearance of the [ZnTPPPA]+Br- was analyzed by
SEM (Figure 6.5). We can see that the [ZnTPPPA]+Br- is a long flatter ribbon-like fibre.
This may be greatly improving the energy transfer. The capacity of visible light absorption
of [ZnTPPPA]+Br- was studied by UV spectrum. As shown in Figure 6.6, there was a
strong signal at 420 nm, therefore, 420 nm-spectrum irradiation was conducted during
the experiment.
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Table 6.1: Reactions of CO2 with epoxide catalyzed by different catalystsa
Entry Catalyst Co-catalyst Visible light Time (h) Isolated yieldb
(%)
1c BrC2COOH -- No 24 0
2 TPP -- No 24 0
3 ZnTPP -- No 24 0
4 [ZnTPPPA]+Br- -- No 24 trace
5 [ZnTPPPA]+Br- -- No 48 3
6 [ZnTPPPA]+Br- -- Yes 20 21 aReaction conditions: epoxide (1.0 ml), catalyst (0.1mol%), CO2 (balloon), 150 W·m-2 visible-
spectrum irradiation (λ= 420 nm), room temperature.bIsolated yield was determined by
weighting method. cBrC2COOH=3-Bromopropionic acid.
Then, the catalytic activities of various porphyrin-based catalysts were carried out
with glycidyl phenyl (GP) and CO2 (balloon) under 420 nm-spectrum irradiation. The
results were shown in Table 6.1. It was found that all the raw materials used to synthesize
of MPILs had no catalytic activity at room temperature (Entries 1-3). However, there was
almost no products generated as catalysed by [ZnTPPPA]+Br- after 24 hours at room
temperature without the spectrum irradiation (Entry 4). When we increased the reaction
time to 48 hours, only 3% yield of CPC obtained (Entry 5). Then the activity of
[ZnTPPPA]+Br- was studied under a spectrum irradiation. To our surprise, [ZnTPPPA]+Br-
showed a 21% isolated yield of corresponding carbonate (Entry 6), which was promising
for realizing the high efficient conversion of CO2 to carbonate at very mind conditions.
Further studies about MPILs together with co-catalyst to improve the catalytic activity
were conducting.
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Conclusions and future work
In this project, we focused on the energy saving of cycloaddition reaction of CO2 with
epoxide to producing cyclic carbonate and the separation process of catalyst and
products. We designed a bunch of highly efficient ionic liquids catalysts for this reaction.
They could be used to catalyze the coupling of CO2 with epoxide under very mild
conditions without high energy input, such as room temperature and 1 bar CO2. An
efficient way to combine activity and recovery of catalysts was also developed for the
separation of ionic liquids catalysts and products. Furthermore, all the ionic liquids
catalysts showed high activity for this reaction. The major work and results for this
dissertation are summarized as follows:
1. A series of carboxylic acid–based functional ionic liquids (CABFILs) were facilely
prepared by one-step synthesis method. They displayed reversible temperature-
controlled phase transitions in PC, which was much useful for the coupling reaction and
separation processes. CABFILs were successfully used in reaction-separation for
conversion of CO2 to carbonates under metal- and solvent-free conditions. Besides, the
IL 3a displayed high activity, and nearly 92% PC yield was obtained within 20 min and
could be readily separated by filtration at room temperature for easy recycle. More
importantly, 3a was suitable for a variety of terminal epoxides. This approach helps to
avoid further waste of the subsequent separation step, as well as a highly effective way
to combine the benefits of heterogeneous and homogenous catalysts, which is of great
interest from the viewpoint of energy saving and chemical engineering.
2. We prepared DBPILs by introducing electron withdrawing groups to O-H acid. The
DBPILs with protonic acid and nucleophilic sites were used as single-component and
metal-free catalysts in the cycloaddition reaction of CO2 with epoxides at very mild
temperature and 1 bar CO2 conditions. DBPILs showed a great improvement of catalytic
activity and good substrate compatibility to various epoxides. Furthermore, DBPILs were
found suitable for the conversion of simulated flue gas. The results from experiments,
spectrum and DFT illustrated the activation of CO2 of DBPILs and strong H-bond
interaction between DBPILs and epoxide. This study provides a highly efficient epoxy
ring-open catalyst for transformation of CO2 with epoxide. The greatly improved catalytic
activity makes DBPILs a promising environmentally benign catalyst for the applications
of CO2 conversion at mild conditions.
3. A powerful DILA with nucleophilic site and aluminum ion was synthesized and
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successfully used as a single-component catalyst in the cycloaddition reaction of CO2
with epoxides at 1 bar CO2 and very mild temperature (25-50oC). It showed excellent
activity under this mild condition and was found to be applicable to various epoxides.
Furthermore, the catalyst could be reused at least four times without any obviously
decrease of catalytic activity. A possible mechanism of ring-opening of epoxide assisted
by aluminium ion and activation of CO2 induced by negative ions of oxygen was proposed.
This work provides a highly efficient and recycling aluminium containing ionic liquids for
conversion of CO2 with epoxide at very mild condition, which is promising for the
applications of CO2 conversion.
4. A series of cross-linked poly(vinylimidazole/butyl acrylate) ionic liquids
membranes (PVBILs) were prepared and used as high efficient heterogeneous catalysts
for fixation of CO2 with epoxide at mild conditions. PVBILs could show comparable
activities in the coupling of epoxide and CO2 with the traditional homogenous catalysts,
because of the activity of CO2 and “homogenous-surroundings” caused by swellable
properties. Swelling behaviour was studied and found to be consistent with the
experimental results of the catalytic activity. The dependence of conversion yield on
catalyst dose, reaction temperature and time were investigated. The best PVBILs could
show a 90% yield of carbonate within 24 hours at 50 oC and 1 bar of CO2. This work
provides a highly efficient way to combine the advantage of homogeneous catalyst and
heterogeneous catalyst, which is promising for the applications of CO2 conversion.
5. A series of metalloporphyrin ionic liquids (MPILs) that combine the advantages of
ionic liquid and porphyrin were designed and synthesized by one step method. The
structure and surface appearance of these BPILs were investigated. These BPILs
catalysts have multiple active sites and a good capacity of visible light absorption due to
the advantages of functional ionic liquids and metal porphyrin part, thus can reduce the
energy inputs greatly by using the visible light. They were successfully used as a
photocatalyst in cycloaddition reaction of CO2 with epoxide to produce carbonate at room
temperature and 1 bar pressure under irradiation of a visible light.
In the future, we will still focus on the energy saving of cycloaddition reaction of CO2
with epoxide to producing cyclic carbonate and the separation process of catalyst and
products. Fixed bed reactor will be used to study PVBILs catalyzed cycloaddition reaction
of CO2 with epoxide. Clear energy such as visible light and electric will be induced as the
energy input to promote this reaction and realize the conversion of CO2 to cyclic
carbonate at very mild conditions.
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References
[1] T. Welton, Room-Temperature Ionic Liquids. Solvents for Synthesis and Catalysis,
Chem. Rev. 99 (1999) 2071-2083. doi:10.1021/cr980032t.
[2] R.D. Rogers, K.R. Seddon, Ionic Liquids - Solvents of the Future?, Science 302
(2003) 792-793. doi:10.1126/science.1090313.
[3] J.P. Hallett, T. Welton, Room-Temperature Ionic Liquids. Solvents for Synthesis and
Catalysis, Chem. Rev. 111 (2011) 3508-3576. doi:10.1021/cr1003248.
[4] P. Walden, “Molecular weights and electrical conductivity of several fused salts,”
Bulletin of the Imperial Academy of Sciences (Saint Petersburg), 1800 (1914) 405–
422. doi:citeulike-article-id:12856962.
[5] N. V. Plechkova, K.R. Seddon, Ionic Liquids: “Designer” Solvents for Green
Chemistry, John Wiley & Sons, Inc. (2007), 103-130.
doi:10.1002/9780470124086.ch5.
[6] X. Han, D.W. Armstrong, Ionic liquids in separations, Acc. Chem. Res.40 (2007)
1079-1086. doi:10.1021/ar700044y.
[7] M. Armand, F. Endres, D.R. MacFarlane, H. Ohno, B. Scrosati, Ionic-liquid materials
for the electrochemical challenges of the future, Nat. Mater. 8 (2009) 621-9.
doi:10.1038/nmat2448.
[8] M.H.G. Prechtl, Nanocatalysis in Ionic Liquids, 2016. doi:10.1002/9783527693283.
[9] J.S. Wilkes, Properties of ionic liquid solvents for catalysis, J. Mol. Catal. A Chem.
214 (2004) 11-17. doi:10.1016/j.molcata.2003.11.029.
[10] J.S. Wilkes, M.J. Zaworotko, Air and water stable 1-ethyl-3-methylimidazolium based
ionic liquids, J. Chem. Soc. Chem. Commun. 23 (1992) 166-166.
doi:10.1039/C39920000965.
[11] Y.S. Sistla, A. Khanna, CO2 absorption studies in amino acid-anion based ionic
liquids, Chem. Eng. J. 273 (2015) 268-276. doi:10.1016/j.cej.2014.09.043.
[12] X. Meng, H. He, Y. Nie, X. Zhang, S. Zhang, J. Wang, Temperature-Controlled
Reaction-Separation for Conversion of CO2 to Carbonates with Functional Ionic
Liquids Catalyst, ACS Sustain. Chem. Eng. 5 (2017) 3081–3086.
doi:10.1021/acssuschemeng.6b02612.
[13] W. Jin, Y. Ke, X. Liu, Q. Yang, Z. Bao, B. Su, Q. Ren, Y. Yang, H. Xing, Enhanced
self-assembly for the solubilization of cholesterol in molecular solvent/ionic liquid
115 | P a g e
mixtures, Phys. Chem. Chem. Phys.19 (2017) 10835-10842.
doi:10.1039/c7cp01098b.
[14] D. Zhao, Z. Fei, T.J. Geldbach, R. Scopelliti, P.J. Dyson, Nitrile-functionalized
pyridinium ionic liquids: Synthesis, characterization, and their application in carbon-
carbon coupling reactions, J. Am. Chem. Soc. 126 (2004) 15876-15882.
doi:10.1021/ja0463482.
[15] M. Yoshizawa-Fujita, Y. Kousa, K. Kidena, A. Ohira, Y. Takeoka, M. Rikukawa,
Proton transport properties in an ionic liquid having a hydroxyl group, Phys. Chem.
Chem. Phys. 13 (2011) 13427-13432. doi:10.1039/c1cp21387c.
[16] H. Zhao, S. V. Malhotra, R.G. Luo, Preparation and characterization of three room-
temperature ionic liquids, Phys. Chem. Liq. 41 (2003) 487- 492.
doi:10.1080/0031910031000155452.
[17] Y. Jin, P. Wang, D. Yin, J. Liu, L. Qin, N. Yu, G. Xie, B. Li, Gold nanoparticles
prepared by sonochemical method in thiol-functionalized ionic liquid, Colloids
Surfaces A Physicochem. Eng. Asp. 302 (2007) 366-370.
doi:10.1016/j.colsurfa.2007.02.060.
[18] J. Ding, D.W. Armstrong, Chiral ionic liquids: Synthesis and applications, Chirality.17
(2005) 281-292. doi:10.1002/chir.20153.
[19] C. Quéré, R. Andrew, P. Friedlingstein, S. Sitch, J. Hauck, J. Pongratz, P. Pickers,
J. Ivar Korsbakken, G. Peters, J. Canadell, A. Arneth, V. Arora, L. Barbero, A. Bastos,
L. Bopp, P. Ciais, L. Chini, P. Ciais, S. Doney, T. Gkritzalis, D. Goll, I. Harris, V.
Haverd, F. Hoffman, M. Hoppema, R. Houghton, G. Hurtt, T. Ilyina, A. Jain, T.
Johannessen, C. Jones, E. Kato, R. Keeling, K. Klein Goldewijk, P. Landschützer, N.
Lefèvre, S. Lienert, Z. Liu, D. Lombardozzi, N. Metzl, D. Munro, J. Nabel, S.I.
Nakaoka, C. Neill, A. Olsen, T. Ono, P. Patra, A. Peregon, W. Peters, P. Peylin, B.
Pfeil, D. Pierrot, B. Poulter, G. Rehder, L. Resplandy, E. Robertson, M. Rocher, C.
Rödenbeck, U. Schuster, I. Skjelvan, R. Séférian, I. Skjelvan, T. Steinhoff, A. Sutton,
P. Tans, H. Tian, B. Tilbrook, F. Tubiello, I. Van Der Laan-Luijkx, G. Van Der Werf,
N. Viovy, A. Walker, A. Wiltshire, R. Wright, S. Zaehle, B. Zheng, Global Carbon
Budget 2018, Earth Syst. Sci. Data. (2018). doi:10.5194/essd-10-2141-2018.
[20] R.R. Shaikh, S. Pornpraprom, V. D’Elia, Catalytic Strategies for the Cycloaddition of
Pure, Diluted, and Waste CO2 to Epoxides under Ambient Conditions, ACS Catal. 8
(2018) 419–450. doi:10.1021/acscatal.7b03580.
116 | P a g e
[21] C. Martín, G. Fiorani, A.W. Kleij, Recent Advances in the Catalytic Preparation of
Cyclic Organic Carbonates, ACS Catal. 5 (2015) 1353–1370.
doi:10.1021/cs5018997.
[22] Q.W. Song, Z.H. Zhou, L.N. He, Efficient, selective and sustainable catalysis of
carbon dioxide, Green Chem. 19 (2017) 3707–3728. doi:10.1039/c7gc00199a.
[23] X.D. Lang, L.N. He, Green Catalytic Process for Cyclic Carbonate Synthesis from
Carbon Dioxide under Mild Conditions, Chem. Rec. (2016) 1337–1352.
doi:10.1002/tcr.201500293.
[24] M. North, R. Pasquale, C. Young, Synthesis of cyclic carbonates from epoxides and
CO2, Green Chem. 12 (2010) 1514–1539. doi:10.1039/c0gc00065e.
[25] C.A. Trickett, A. Helal, B.A. Al-Maythalony, Z.H. Yamani, K.E. Cordova, O.M. Yaghi,
The chemistry of metal-organic frameworks for CO2 capture, regeneration and
conversion, Nat. Rev. Mater. 2 (2017). doi:10.1038/natrevmats.2017.45.
[26] H.-Q. Xu, J. Hu, D. Wang, Z. Li, Q. Zhang, Y. Luo, S.-H. Yu, H.-L. Jiang, Visible-Light
Photoreduction of CO2 in a Metal–Organic Framework: Boosting Electron–Hole
Separation via Electron Trap States, J. Am. Chem. Soc. 137 (2015) 13440–13443.
doi:10.1021/jacs.5b08773.
[27] N. von der Assen, J. Jung, A. Bardow, Life-cycle assessment of carbon dioxide
capture and utilization: avoiding the pitfalls, Energy Environ. Sci. 6 (2013) 2721–2734.
doi:10.1039/C3EE41151F.
[28] C. Wulf, J. Steinbauer, H. Büttner, T. Werner, L. Longwitz, Recent Developments in
the Synthesis of Cyclic Carbonates from Epoxides and CO2, Top. Curr. Chem. 375
(2017) 50. doi:10.1007/s41061-017-0136-5.
[29] W.N.R. Wan Isahak, Z.A. Che Ramli, M.W. Mohamed Hisham, M.A. Yarmo, The
formation of a series of carbonates from carbon dioxide: Capturing and utilisation,
Renew. Sustain. Energy Rev. 47 (2015) 93-106. doi:10.1016/j.rser.2015.03.020.
[30] H. Zhou, G.X. Wang, W.Z. Zhang, X.B. Lu, CO2 Adducts of Phosphorus Ylides:
Highly Active Organocatalysts for Carbon Dioxide Transformation, ACS Catal. 5
(2015) 6773–6779. doi:10.1021/acscatal.5b01409.
[31] M. Cheng, E.B. Lobkovsky, G.W. Coates, Catalytic reactions involving C1 feedstocks:
New high-activity Zn(II)- based catalysts for the alternating copolymerization of
carbon dioxide and epoxides, J. Am. Chem. Soc. 120 (1998) 11018-11019.
doi:10.1021/ja982601k.
117 | P a g e
[32] R.L. Paddock, Y. Hiyama, J.M. McKay, S.B.T. Nguyen, Co(III) porphyrin/DMAP: An
efficient catalyst system for the synthesis of cyclic carbonates from CO2 and
epoxides, Tetrahedron Lett. 45 (2004) 2023-2026. doi:10.1016/j.tetlet.2003.10.101.
[33] S. Lawrenson, M. North, F. Peigneguy, A. Routledge, Greener solvents for solid-
phase synthesis, Green Chem. 19 (2017) 952–962. doi:10.1039/C6GC03147A.
[34] S.B. Lawrenson, R. Arav, M. North, The greening of peptide synthesis, Green Chem.
19 (2017) 1685–1691. doi:10.1039/C7GC00247E.
[35] M. North, P. Villuendas, A Chiral Solvent Effect in Asymmetric Organocatalysis, Org.
Lett. 12 (2010) 2378–2381. doi:10.1021/ol1007313.
[36] X. Wei, W. Xu, M. Vijayakumar, L. Cosimbescu, T. Liu, V. Sprenkle, W. Wang,
TEMPO-based catholyte for high-energy density nonaqueous redox flow batteries,
Adv. Mater. 26 (2014) 7649–7653. doi:10.1002/adma.201403746.
[37] M. Blain, H. Yau, L. Jean-Gérard, R. Auvergne, D. Benazet, P.R. Schreiner, S. Caillol,
B. Andrioletti, Urea-and thiourea-catalyzed aminolysis of carbonates,
ChemSusChem. 9 (2016) 2269–2272. doi:10.1002/cssc.201600778.
[38] W. Guo, J. Gõnzalez-Fabra, N.A.G. Bandeira, C. Bo, A.W. Kleij, A Metal-Free
Synthesis of N-Aryl Carbamates under Ambient Conditions, Angew. Chemie - Int. Ed.
54 (2015) 11686–11690. doi:10.1002/anie.201504956.
[39] P. Kumar, V.C. Srivastava, I.M. Mishra, Synthesis and characterization of Ce-La
oxides for the formation of dimethyl carbonate by transesterification of propylene
carbonate, Catal. Commun. 60 (2015) 27–31. doi:10.1016/j.catcom.2014.11.006.
[40] J. Xie, W. Guo, A. Cai, E.C. Escudero-Adán, A.W. Kleij, Pd-Catalyzed Enantio- and
Regioselective Formation of Allylic Aryl Ethers, Org. Lett. 19 (2017) 6388–6391.
doi:10.1021/acs.orglett.7b03247.
[41] A. Cai, W. Guo, L. Martínez-Rodríguez, A.W. Kleij, Palladium-Catalyzed Regio- and
Enantioselective Synthesis of Allylic Amines Featuring Tetrasubstituted Tertiary
Carbons, J. Am. Chem. Soc. 138 (2016) 14194–14197. doi:10.1021/jacs.6b08841.
[42] J. Nemirowsky, Ueber die Einwirkung von Chlorkohlenoxyd auf Aethylenglycol;
vorläufige Mittheilung, J. Für Prakt. Chemie. 28 (2005) 439–440.
doi:10.1002/prac.18830280136.
[43] W.H. Carothers, G.L. Borough, F.J. Natta, Studies of polymerization and ring
formation. X. The reversible polymerization of six-membered cyclic esters, J. Am.
Chem. Soc. 54 (1932) 761-772. doi:10.1021/ja01341a046.
118 | P a g e
[44] J. Song, Z. Zhang, B. Han, S. Hu, W. Li, Y. Xie, Synthesis of cyclic carbonates from
epoxides and CO2 catalyzed by potassium halide in the presence of β-cyclodextrin,
Green Chem. 10 (2008) 1337–1341. doi:10.1039/b815105a.
[45] B. Zhang, H. Fan, J. Song, J. Liu, J. Ma, P. Zhang, B. Han, T. Jiang, Highly efficient
synthesis of cyclic carbonates from CO2 and epoxides catalyzed by KI/lecithin, Catal.
Today. 183 (2012) 130–135. doi:10.1016/j.cattod.2011.08.042.
[46] S. Liang, H. Liu, T. Jiang, J. Song, G. Yang, B. Han, Highly efficient synthesis of
cyclic carbonates from CO2 and epoxides over cellulose/KI, Chem. Commun. 47
(2011) 2131–2133. doi:10.1039/c0cc04829a.
[47] J. Ma, J. Liu, Z. Zhang, B. Han, The catalytic mechanism of KI and the co-catalytic
mechanism of hydroxyl substances for cycloaddition of CO2 with propylene oxide,
Green Chem. 14 (2012) 2410–2420. doi:10.1039/c2gc35711a.
[48] T. Werner, N. Tenhumberg, Synthesis of cyclic carbonates from epoxides and CO2
catalyzed by potassium iodide and amino alcohols, J. CO2 Util. 7 (2014) 39–45.
doi:10.1016/j.jcou.2014.04.002.
[49] W. Desens, C. Kohrt, M. Frank, T. Werner, Highly Efficient Polymer-Supported
Catalytic System for the Valorization of Carbon Dioxide, ChemSusChem. 8 (2015)
3815–3822. doi:10.1002/cssc.201501119.
[50] S. Kaneko, S. Shirakawa, Potassium Iodide-Tetraethylene Glycol Complex as a
Practical Catalyst for CO2 Fixation Reactions with Epoxides under Mild Conditions,
ACS Sustain. Chem. Eng. 5 (2017) 2836–2840.
doi:10.1021/acssuschemeng.7b00324.
[51] C. Qiao, X. Cui, T. Lin, Z. Bu, Q. Li, H. Wang, H. Chang, Conversion of carbon dioxide
into cyclic carbonates using wool powder-KI as catalyst, J. CO2 Util. 24 (2018) 174–
179. doi:10.1016/j.jcou.2017.12.017.
[52] P. Ramidi, P. Munshi, Y. Gartia, S. Pulla, A.S. Biris, A. Paul, A. Ghosh, Synergistic
effect of alkali halide and Lewis base on the catalytic synthesis of cyclic carbonate
from CO2 and epoxide, Chem. Phys. Lett. 512 (2011) 273–277.
doi:10.1016/j.cplett.2011.07.035.
[53] X. Liu, S. Zhang, Q.W. Song, X.F. Liu, R. Ma, L.N. He, Cooperative calcium-based
catalysis with 1,8-diazabicyclo[5.4.0]-undec-7-ene for the cycloaddition of epoxides
with CO2 at atmospheric pressure, Green Chem. 18 (2016) 2871–2876.
doi:10.1039/c5gc02761f.
119 | P a g e
[54] J. Peng, S. Wang, H.J. Yang, B. Ban, Z. Wei, L. Wang, L. Bo, Chemical fixation of
CO2 to cyclic carbonate catalyzed by new environmental- friendly bifunctional bis-β-
cyclodextrin derivatives, Catal. Today. 330 (2018) 76-84.
doi:10.1016/j.cattod.2018.06.020.
[55] M. Liu, B. Liu, L. Shi, F. Wang, L. Liang, J. Sun, Melamine-ZnI2 as heterogeneous
catalysts for efficient chemical fixation of carbon dioxide to cyclic carbonates, RSC
Adv. 5 (2015) 960–966. doi:10.1039/c4ra11460d.
[56] J. Tharun, G. Mathai, A.C. Kathalikkattil, R. Roshan, J.Y. Kwak, D.W. Park,
Microwave-assisted synthesis of cyclic carbonates by a formic acid/KI catalytic
system, Green Chem. 15 (2013) 1673–1677. doi:10.1039/c3gc40729b.
[57] M. Liu, B. Liu, S. Zhong, L. Shi, L. Liang, J. Sun, Kinetics and mechanistic insight
into efficient fixation of CO2 to epoxides over N-heterocyclic compound/ZnBr2
catalysts, Ind. Eng. Chem. Res. 54 (2015) 633–640. doi:10.1021/ie5042879.
[58] Z. Wu, H. Xie, X. Yu, E. Liu, Lignin-Based Green Catalyst for the Chemical Fixation
of Carbon Dioxide with Epoxides To Form Cyclic Carbonates under Solvent-Free
Conditions, ChemCatChem. 5 (2013) 1328–1333. doi:10.1002/cctc.201200894.
[59] W. Chen, L.X. Zhong, X.W. Peng, R.C. Sun, F.C. Lu, Chemical fixation of carbon
dioxide using a green and efficient catalytic system based on sugarcane bagasse-
an agricultural waste, ACS Sustain. Chem. Eng. 3 (2015) 147–152.
doi:10.1021/sc5006445.
[60] Y. Ren, J.-J. Shim, ChemInform Abstract: Efficient Synthesis of Cyclic Carbonates
by Mg II /Phosphine-Catalyzed Coupling Reactions of Carbon Dioxide and
Epoxides. , ChemInform. 44 (2013) no-no. doi:10.1002/chin.201344115.
[61] K. Tomishige, H. Yasuda, Y. Yoshida, M. Nurunnabi, B. Li, K. Kunimori, Catalytic
performance and properties of ceria based catalysts for cyclic carbonate synthesis
from glycol and carbon dioxide, Green Chem. 6 (2004) 206–214.
doi:10.1039/b401215a.
[62] K. Kaneda, H. Yoshida, K. Ebitani, K. Yamaguchi, T. Yoshida, Mg−Al Mixed Oxides
as Highly Active Acid−Base Catalysts for Cycloaddition of Carbon Dioxide to
Epoxides, J. Am. Chem. Soc. 121 (2002) 4526–4527. doi:10.1021/ja9902165.
[63] A. Dhakshinamoorthy, A.M. Asiri, M. Alvaro, H. Garcia, Metal organic frameworks as
catalysts in solvent-free or ionic liquid assisted conditions, Green Chem. 20 (2018)
86–107. doi:10.1039/c7gc02260c.
120 | P a g e
[64] H. Rao, L.C. Schmidt, J. Bonin, M. Robert, Visible-light-driven methane formation
from CO2 with a molecular iron catalyst, Nature. 548 (2017) 74–77.
doi:10.1038/nature23016.
[65] X. Gao, M. Liu, J. Lan, L. Liang, X. Zhang, J. Sun, Lewis acid−base bifunctional
crystals with a three-dimensional framework for selective coupling of CO2 and
epoxides under mild and solvent-free conditions, Cryst. Growth Des. 17 (2017) 51–
57. doi:10.1021/acs.cgd.6b01132.
[66] B. Mousavi, S. Chaemchuen, B. Moosavi, Z. Luo, N. Gholampour, F. Verpoort,
Zeolitic imidazole framework-67 as an efficient heterogeneous catalyst for the
conversion of CO2to cyclic carbonates, New J. Chem. 40 (2016) 5170–5176.
doi:10.1039/c6nj00128a.
[67] P.T.K. Nguyen, H.T.D. Nguyen, H.N. Nguyen, C.A. Trickett, Q.T. Ton, E. Gutiérrez-
Puebla, M.A. Monge, K.E. Cordova, F. Gándara, New Metal-Organic Frameworks
for Chemical Fixation of CO2, ACS Appl. Mater. Interfaces. 10 (2018) 733–744.
doi:10.1021/acsami.7b16163.
[68] R.R. Kuruppathparambil, T. Jose, R. Babu, G.Y. Hwang, A.C. Kathalikkattil, D.W.
Kim, D.W. Park, A room temperature synthesizable and environmental friendly
heterogeneous ZIF-67 catalyst for the solvent less and co-catalyst free synthesis of
cyclic carbonates, Appl. Catal. B Environ. 182 (2016) 562–569.
doi:10.1016/j.apcatb.2015.10.005.
[69] D.A. Yang, H.Y. Cho, J. Kim, S.T. Yang, W.S. Ahn, CO2 capture and conversion
using Mg-MOF-74 prepared by a sonochemical method, Energy Environ. Sci. 5
(2012) 6465–6473. doi:10.1039/c1ee02234b.
[70] Z. Zhou, C. He, J. Xiu, L. Yang, C. Duan, Metal-Organic Polymers Containing
Discrete Single-Walled Nanotube as a Heterogeneous Catalyst for the Cycloaddition
of Carbon Dioxide to Epoxides, J. Am. Chem. Soc. 137 (2015) 15066–15069.
doi:10.1021/jacs.5b07925.
[71] C.M. Miralda, E.E. Macias, M. Zhu, P. Ratnasamy, M.A. Carreon, Zeolitic Imidazole
Framework-8 Catalysts in the Conversion of CO2 to Chloropropene Carbonate, ACS
Catal. 2 (2012) 180–183. doi:10.1021/cs200638h.
[72] H.J. Kim, J.F. Kurisingal, D.W. Park, Ni2(BDC)2(DABCO) metal–organic framework
for cyclic carbonate synthesis from CO2 and epoxides (BDC = 1,4-
121 | P a g e
benzendicarboxylic acid, DABCO = 1,4-diazabicyclo[2.2.2]octane), React. Kinet.
Mech. Catal. 124 (2018) 335–346. doi:10.1007/s11144-018-1356-6.
[73] S. Chaemchuen, X. Xiao, M. Ghadamyari, B. Mousavi, N. Klomkliang, Y. Yuan, F.
Verpoort, Robust and efficient catalyst derived from bimetallic Zn/Co zeolitic
imidazolate frameworks for CO2 conversion, J. Catal. 370 (2019) 38–45.
doi:10.1016/j.jcat.2018.11.027.
[74] C. Maeda, T. Taniguchi, K. Ogawa, T. Ema, Bifunctional catalysts based on m-
phenylene-bridged porphyrin dimer and trimer platforms: Synthesis of cyclic
carbonates from carbon dioxide and epoxides, Angew. Chemie-Int. Ed. 54 (2015)
134–138. doi:10.1002/anie.201409729.
[75] T. Ema, Y. Miyazaki, J. Shimonishi, C. Maeda, J.Y. Hasegawa, Bifunctional porphyrin
catalysts for the synthesis of cyclic carbonates from epoxides and CO2: Structural
optimization and mechanistic study, J. Am. Chem. Soc. 136 (2014) 15270–15279.
doi:10.1021/ja507665a.
[76] W. Wang, Y. Wang, C. Li, L. Yan, M. Jiang, Y. Ding, State-of-the-Art Multifunctional
Heterogeneous POP Catalyst for Cooperative Transformation of CO2 to Cyclic
Carbonates, ACS Sustain. Chem. Eng. 5 (2017) 4523–4528.
doi:10.1021/acssuschemeng.7b00947.
[77] X. Jiang, F. Gou, F. Chen, H. Jing, Cycloaddition of epoxides and CO2 catalyzed by
bisimidazole-functionalized porphyrin cobalt(III) complexes, Green Chem. 18 (2016)
3567–3576. doi:10.1039/c6gc00370b.
[78] P.G. Cozzi, Metal-Salen Schiff base complexes in catalysis: Practical aspects, Chem.
Soc. Rev. (2004). doi:10.1039/b307853c.
[79] S. He, F. Wang, W.L. Tong, S.M. Yiu, M.C.W. Chan, Topologically diverse shape-
persistent bis-(Zn-salphen) catalysts: efficient cyclic carbonate formation under mild
conditions, Chem. Commun. (2016). doi:10.1039/c5cc08794e.
[80] R.L. Paddock, S.T. Nguyen, Chiral (Salen)CoIII Catalyst for the Synthesis of Cyclic
Carbonates., ChemInform. (2004). doi:10.1002/chin.200447113.
[81] X. Zhang, Y.B. Jia, X.B. Lu, B. Li, H. Wang, L.C. Sun, Intramolecularly two-centered
cooperation catalysis for the synthesis of cyclic carbonates from CO2 and epoxides,
Tetrahedron Lett. (2008). doi:10.1016/j.tetlet.2008.09.035.
[82] A. Decortes, M. Martínez Belmonte, J. Benet-Buchholz, A.W. Kleij, Efficient
carbonate synthesis under mild conditions through cycloaddition of carbon dioxide to
122 | P a g e
oxiranes using a Zn(salphen) catalyst, Chem. Commun. (2010).
doi:10.1039/c000493f.
[83] F. Castro-Gómez, G. Salassa, A.W. Kleij, C. Bo, A DFT study on the mechanism of
the cycloaddition reaction of CO2 to epoxides catalyzed by Zn(Salphen) complexes,
Chem. - A Eur. J. (2013). doi:10.1002/chem.201203985.
[84] X.B. Lu, Y.J. Zhang, B. Liang, X. Li, H. Wang, Chemical fixation of carbon dioxide to
cyclic carbonates under extremely mild conditions with highly active bifunctional
catalysts, J. Mol. Catal. A Chem. (2004). doi:10.1016/j.molcata.2003.09.010.
[85] D.F. Smith, S. Balagura, Role of oropharyngeal factors in LiCl aversion, J. Comp.
Physiol. Psychol. 69 (1969) 308–310. doi:10.1037/h0028228.
[86] M. Ikiz, E. Ispir, E. Aytar, M. Ulusoy, Ş. Karabuʇa, M. Aslantaş, Ö. Çelik, Chemical
fixation of CO2 into cyclic carbonates by azo-containing Schiff base metal complexes,
New J. Chem. (2015). doi:10.1039/c5nj00571j.
[87] J. Miao, J. Xue, J. Zhu, K. Liu, CO2 capture and conversion using a cobalt(III) schiff
base complex as a catalyst at ambient conditions, in: EPD Congr. 2015, 2016.
doi:10.1007/978-3-319-48214-9_14.
[88] T. Hirose, S. Qu, K. Kodama, X. Wang, Organocatalyst system for disubstituted
carbonates from cycloaddition between CO2 and internal epoxides, J. CO2 Util. 24
(2018) 261–265. doi:10.1016/j.jcou.2018.01.016.
[89] W. Cho, M.S. Shin, S. Hwang, H. Kim, M. Kim, J.G. Kim, Y. Kim, Tertiary amines: A
new class of highly efficient organocatalysts for CO2 fixations, J. Ind. Eng. Chem. 44
(2016) 210–215. doi:10.1016/j.jiec.2016.09.015.
[90] S.R. Jagtap, V.P. Raje, S.D. Samant, B.M. Bhanage, Silica supported polyvinyl
pyridine as a highly active heterogeneous base catalyst for the synthesis of cyclic
carbonates from carbon dioxide and epoxides, J. Mol. Catal. A Chem. (2007).
doi:10.1016/j.molcata.2006.10.033.
[91] S. Arayachukiat, C. Kongtes, A. Barthel, S.V.C. Vummaleti, A. Poater, S. Wannakao,
L. Cavallo, V. D’Elia, Ascorbic Acid as a Bifunctional Hydrogen Bond Donor for the
Synthesis of Cyclic Carbonates from CO2 under Ambient Conditions, ACS Sustain.
Chem. Eng. 5 (2017) 6392–6397. doi:10.1021/acssuschemeng.7b01650.
[92] X. Zhang, N. Zhao, W. Wei, Y. Sun, Chemical fixation of carbon dioxide to propylene
carbonate over amine-functionalized silica catalysts, Catal. Today. (2006).
doi:10.1016/j.cattod.2006.02.028.
123 | P a g e
[93] B. Chatelet, L. Joucla, J.P. Dutasta, A. Martinez, K.C. Szeto, V. Dufaud,
Azaphosphatranes as structurally tunable organocatalysts for carbonate synthesis
from CO2and epoxides, J. Am. Chem. Soc. 135 (2013) 5348–5351.
doi:10.1021/ja402053d.
[94] A. Barbarini, R. Maggi, A. Mazzacani, G. Mori, G. Sartori, R. Sartorio, Cycloaddition
of CO2 to epoxides over both homogeneous and silica-supported guanidine catalysts,
Tetrahedron Lett. (2003). doi:10.1016/S0040-4039(03)00424-6.
[95] C.J. Whiteoak, A. Nova, F. Maseras, A.W. Kleij, Merging sustainability with
organocatalysis in the formation of organic carbonates by using CO2 as a feedstock,
ChemSusChem. (2012). doi:10.1002/cssc.201200255.
[96] J. Wang, Y. Zhang, Boronic Acids as Hydrogen Bond Donor Catalysts for Efficient
Conversion of CO2 into Organic Carbonate in Water, ACS Catal. 6 (2016) 4871–
4876. doi:10.1021/acscatal.6b01422.
[97] K.R. Roshan, T. Jose, A.C. Kathalikkattil, D.W. Kim, B. Kim, D.W. Park, Microwave
synthesized quaternized celluloses for cyclic carbonate synthesis from carbon
dioxide and epoxides, Appl. Catal. A Gen. (2013). doi:10.1016/j.apcata.2013.07.007.
[98] J. Sun, W. Cheng, Z. Yang, J. Wang, T. Xu, J. Xin, S. Zhang, Superbase/cellulose:
An environmentally benign catalyst for chemical fixation of carbon dioxide into cyclic
carbonates, Green Chem. (2014). doi:10.1039/c3gc41850b.
[99] S. Wang, J. Peng, H.-J. Yang, B. Ban, L. Wang, B. Lei, C.-Y. Guo, J. Hu, J. Zhu, B.
Han, β-Cyclodextrin/Quaternary Ammonium Salt as an Efficient Catalyst System
for Chemical Fixation of CO 2 , J. Nanosci. Nanotechnol. (2019).
doi:10.1166/jnn.2019.16610.
[100] J. Tharun, K.R. Roshan, A.C. Kathalikkattil, D.H. Kang, H.M. Ryu, D.W. Park,
Natural amino acids/H2O as a metal- and halide-free catalyst system for the
synthesis of propylene carbonate from propylene oxide and CO2under moderate
conditions, RSC Adv. 40 (2014) 41266–41270. doi:10.1039/c4ra06964a.
[101] G.P. Wu, D.J. Darensbourg, Mechanistic Insights into Water-Mediated Tandem
Catalysis of Metal-Coordination CO2/Epoxide Copolymerization and Organocatalytic
Ring-Opening Polymerization: One-Pot, Two Steps, and Three Catalysis Cycles for
Triblock Copolymers Synthesis, Macromolecules. (2016).
doi:10.1021/acs.macromol.5b02752.
124 | P a g e
[102] J. Sun, J. Ren, S. Zhang, W. Cheng, Water as an efficient medium for the synthesis
of cyclic carbonate, Tetrahedron Lett. (2009). doi:10.1016/j.tetlet.2008.11.034.
[103] Y.M. Shen, W.L. Duan, M. Shi, Chemical fixation of carbon dioxide co-catalyzed by
a combination of Schiff bases or phenols and organic bases, European J. Org. Chem.
(2004). doi:10.1002/ejoc.200400083.
[104] K.R. Roshan, R.A. Palissery, A.C. Kathalikkattil, R. Babu, G. Mathai, H.S. Lee, D.W.
Park, A computational study of the mechanistic insights into base catalysed
synthesis of cyclic carbonates from CO2: Bicarbonate anion as an active species,
Catal. Sci. Technol. (2016). doi:10.1039/c5cy01902h.
[105] J. Sun, W. Cheng, Z. Yang, J. Wang, T. Xu, J. Xin, S. Zhang, Superbase/cellulose:
An environmentally benign catalyst for chemical fixation of carbon dioxide into cyclic
carbonates, Green Chem. 16 (2014) 3071–3078. doi:10.1039/c3gc41850b.
[106] J.Q. Wang, W.G. Cheng, J. Sun, T.Y. Shi, X.P. Zhang, S.J. Zhang, Efficient fixation
of CO2 into organic carbonates catalyzed by 2-hydroxymethyl-functionalized ionic
liquids, RSC Adv. 4 (2014) 2360–2367. doi:10.1039/c3ra45918g.
[107] J. Sun, S. Zhang, W. Cheng, J. Ren, Hydroxyl-functionalized ionic liquid: a novel
efficient catalyst for chemical fixation of CO2 to cyclic carbonate, Tetrahedron Lett.
49 (2008) 3588–3591. doi:10.1016/j.tetlet.2008.04.022.
[108] H.C. Cho, H.S. Lee, J. Chun, S.M. Lee, H.J. Kim, S.U. Son, Tubular microporous
organic networks bearing imidazolium salts and their catalytic CO2conversion to
cyclic carbonates, Chem. Commun. 47 (2011) 917–919. doi:10.1039/c0cc03914d.
[109] M.H. Anthofer, M.E. Wilhelm, M. Cokoja, M. Drees, W.A. Herrmann, F.E. Kühn,
Hydroxy-functionalized imidazolium bromides as catalysts for the cycloaddition of
CO2 and epoxides to cyclic carbonates, ChemCatChem. 7 (2015) 94–98.
doi:10.1002/cctc.201402754.
[110] J. Sun, L. Han, W. Cheng, J. Wang, X. Zhang, S. Zhang, Efficient acid-base
bifunctional catalysts for the fixation of CO2 with epoxides under metal- and solvent-
free conditions, ChemSusChem. 4 (2011) 502–507. doi:10.1002/cssc.201000305.
[111] F. Liu, K. Huang, Q. Wu, S. Dai, Solvent-Free Self-Assembly to the Synthesis of
Nitrogen-Doped Ordered Mesoporous Polymers for Highly Selective Capture and
Conversion of CO2, Adv. Mater. 29 (2017) 1–8. doi:10.1002/adma.201700445.
125 | P a g e
[112] J. Li, D. Jia, Z. Guo, Y. Liu, Y. Lyu, Y. Zhou, J. Wang, Imidazolinium based porous
hypercrosslinked ionic polymers for efficient CO2 capture and fixation with epoxides,
Green Chem. 19 (2017) 2675–2686. doi:10.1039/c7gc00105c.
[113] A. Mirabaud, J.C. Mulatier, A. Martinez, J.P. Dutasta, V. Dufaud, Investigating Host-
Guest Complexes in the Catalytic Synthesis of Cyclic Carbonates from Styrene
Oxide and CO2, ACS Catal. 5 (2015) 6748–6752. doi:10.1021/acscatal.5b01545.
[114] B. Chatelet, L. Joucla, J.P. Dutasta, A. Martinez, K.C. Szeto, V. Dufaud,
Azaphosphatranes as structurally tunable organocatalysts for carbonate synthesis
from CO2 and epoxides, J. Am. Chem. Soc. 135 (2013) 5348–5351.
doi:10.1021/ja402053d.
[115] T. Werner, H. Büttner, Phosphorus-based bifunctional organocatalysts for the
addition of carbon dioxide and epoxides, ChemSusChem. 7 (2014) 3268–3271.
doi:10.1002/cssc.201402477.
[116] J. Großeheilmann, H. Büttner, C. Kohrt, U. Kragl, T. Werner, Recycling of
phosphorus-based organocatalysts by organic solvent nanofiltration, ACS Sustain.
Chem. Eng. 3 (2015) 2817–2822. doi:10.1021/acssuschemeng.5b00734.
[117] Z. Zhang, F. Fan, H. Xing, Q. Yang, Z. Bao, Q. Ren, Efficient Synthesis of Cyclic
Carbonates from Atmospheric CO2 Using a Positive Charge Delocalized Ionic Liquid
Catalyst, ACS Sustain. Chem. Eng. 5 (2017) 2841–2846.
doi:10.1021/acssuschemeng.7b00513.
[118] M. Liu, X. Li, L. Liang, J. Sun, Protonated triethanolamine as multi-hydrogen bond
donors catalyst for efficient cycloaddition of CO2 to epoxides under mild and
cocatalyst-free conditions, J. CO2 Util. 16 (2016) 384–390.
doi:10.1016/j.jcou.2016.10.004.
[119] H. Büttner, K. Lau, A. Spannenberg, T. Werner, Bifunctional one-component
catalysts for the addition of carbon dioxide to epoxides, ChemCatChem. 7 (2015)
459–467. doi:10.1002/cctc.201402816.
[120] S. Duan, X. Jing, D. Li, H. Jing, Catalytic asymmetric cycloaddition of CO2 to
epoxides via chiral bifunctional ionic liquids, J. Mol. Catal. A Chem. 411 (2016) 34–
39. doi:10.1016/j.molcata.2015.10.008.
[121] J. Tharun, K.M. Bhin, R. Roshan, D.W. Kim, A.C. Kathalikkattil, R. Babu, H.Y. Ahn,
Y.S. Won, D.W. Park, Ionic liquid tethered post functionalized ZIF-90 framework for
126 | P a g e
the cycloaddition of propylene oxide and CO2, Green Chem. 18 (2016) 2479–2487.
doi:10.1039/c5gc02153g.
[122] D. Kim, Y. Moon, D. Ji, H. Kim, D. Cho, Metal-containing ionic liquids as synergistic
catalysts for the cycloaddition of CO2: A density functional theory and response
surface methodology corroborated study, ACS Sustain. Chem. Eng. 4 (2016) 4591–
4600. doi:10.1021/acssuschemeng.6b00711.
[123] Q. Su, X. Yao, W. Cheng, S. Zhang, Boron-doped melamine-derived carbon nitrides
tailored by ionic liquids for catalytic conversion of CO2into cyclic carbonates, Green
Chem. 19 (2017) 2957–2965. doi:10.1039/c7gc00279c.
[124] Q. He, J.W. O’Brien, K.A. Kitselman, L.E. Tompkins, G.C.T. Curtis, F.M. Kerton,
Synthesis of cyclic carbonates from CO2 and epoxides using ionic liquids and related
catalysts including choline chloride-metal halide mixtures, Catal. Sci. Technol. 4
(2014) 1513–1528. doi:10.1039/c3cy00998j.
[125] J. Zhu, T. Diao, W. Wang, X. Xu, X. Sun, S.A.C. Carabineiro, Z. Zhao, Boron doped
graphitic carbon nitride with acid-base duality for cycloaddition of carbon dioxide to
epoxide under solvent-free condition, Appl. Catal. B Environ. 219 (2017) 92–100.
doi:10.1016/j.apcatb.2017.07.041.
[126] J. Steinbauer, L. Longwitz, M. Frank, J. Epping, U. Kragl, T. Werner, Immobilized
bifunctional phosphonium salts as recyclable organocatalysts in the cycloaddition of
CO2 and epoxides, Green Chem. 19 (2017) 4435–4445. doi:10.1039/c7gc01782k.
[127] B. Chatelet, L. Joucla, J.P. Dutasta, A. Martinez, V. Dufaud, Immobilization of a N-
substituted azaphosphatrane in nanopores of SBA-15 silica for the production of
cyclic carbonates, J. Mater. Chem. A. 2 (2014) 14164–14172.
doi:10.1039/c4ta01500b.
[128] Q.W. Song, L.N. He, J.Q. Wang, H. Yasuda, T. Sakakura, Catalytic fixation of CO2
to cyclic carbonates by phosphonium chlorides immobilized on fluorous polymer,
Green Chem. 15 (2013) 110–115. doi:10.1039/c2gc36210d.
[129] T. Ying, X. Tan, Q. Su, W. Cheng, L. Dong, S. Zhang, Polymeric ionic liquids tailored
by different chain groups for the efficient conversion of CO2 into cyclic carbonates,
Green Chem. (2019). doi:10.1039/C9GC00010K.
[130] J.Q. Wang, J. Sun, W.G. Cheng, K. Dong, X.P. Zhang, S.J. Zhang, Experimental
and theoretical studies on hydrogen bond-promoted fixation of carbon dioxide and
127 | P a g e
epoxides in cyclic carbonates, Phys. Chem. Chem. Phys. 14 (2012) 11021–11026.
doi:10.1039/c2cp41698k.
[131] J. Peng, Y. Deng, Cycloaddition of carbon dioxide to propylene oxide catalyzed by
ionic liquids, New J. Chem. 25 (2001) 639–641. doi:10.1039/b008923k.
[132] H. Kawanami, A. Sasaki, K. Matsui, Y. Ikushima, A rapid and effective synthesis of
propylene carbonate using a supercritical CO2-ionic liquid system, Chem. Commun.
(2003). doi:10.1039/b212823c.
[133] H.S. Kim, J.J. Kim, H. Kim, H.G. Jang, Imidazolium zinc tetrahalide-catalyzed
coupling reaction of CO2 and ethylene oxide or propylene oxide, J. Catal. (2003).
doi:10.1016/S0021-9517(03)00238-0.
[134] F. Li, L. Xiao, C. Xia, B. Hu, Chemical fixation of CO2 with highly efficient ZnCl
2/[BMIm]Br catalyst system, Tetrahedron Lett. (2004).
doi:10.1016/j.tetlet.2004.09.074.
[135] V. Caló, A. Nacci, A. Monopoli, A. Fanizzi, Cyclic carbonate formation from carbon
dioxide and oxiranes in tetrabutylammonium halides as solvents and catalysts, Org.
Lett. (2002). doi:10.1021/ol026189w.
[136] M. North, R. Pasquale, Mechanism of cyclic carbonate synthesis from epoxides and
CO2, Angew. Chemie - Int. Ed. 48 (2009) 2946–2948. doi:10.1002/anie.200805451.
[137] Z.Z. Yang, L.N. He, C.X. Miao, S. Chanfreau, Lewis basic ionic liquids-catalyzed
conversion of carbon dioxide to cyclic carbonates, Adv. Synth. Catal. (2010).
doi:10.1002/adsc.201000239.
[138] S. Foltran, R. Mereau, T. Tassaing, Theoretical study on the chemical fixation of
carbon dioxide with propylene oxide catalyzed by ammonium and guanidinium salts,
Catal. Sci. Technol. (2014). doi:10.1039/c3cy00955f.
[139] T. Takahashi, T. Watahiki, S. Kitazume, H. Yasuda, T. Sakakura, Synergistic hybrid
catalyst for cyclic carbonate synthesis: Remarkable acceleration caused by
immobilization of homogeneous catalyst on silica, Chem. Commun. (2006).
doi:10.1039/b517140g.
[140] J. Sun, J. Wang, W. Cheng, J. Zhang, X. Li, S. Zhang, Y. She, Chitosan
functionalized ionic liquid as a recyclable biopolymer-supported catalyst for
cycloaddition of CO 2, Green Chem. 14 (2012) 654–660. doi:10.1039/c2gc16335g.
[141] L. Han, H.J. Choi, S.J. Choi, B. Liu, D.W. Park, Ionic liquids containing carboxyl acid
moieties grafted onto silica: Synthesis and application as heterogeneous catalysts
128 | P a g e
for cycloaddition reactions of epoxide and carbon dioxide, Green Chem. (2011).
doi:10.1039/c0gc00612b.
[142] Q. Su, Y. Qi, X. Yao, W. Cheng, L. Dong, S. Chen, S. Zhang, Ionic liquids tailored
and confined by one-step assembly with mesoporous silica for boosting the catalytic
conversion of CO2 into cyclic carbonates, Green Chem. (2018).
doi:10.1039/c8gc01038b.
[143] Y. Xie, Z. Zhang, T. Jiang, J. He, B. Han, T. Wu, K. Ding, CO2 cycloaddition
reactions catalyzed by an ionic liquid grafted onto a highly cross-linked polymer
matrix, Angew. Chemie - Int. Ed. 46 (2007) 7255–7258. doi:10.1002/anie.200701467.
[144] T.Y. Shi, J.Q. Wang, J. Sun, M.H. Wang, W.G. Cheng, S.J. Zhang, Efficient fixation
of CO<inf>2</inf> into cyclic carbonates catalyzed by hydroxyl-functionalized
poly(ionic liquids), RSC Adv. (2013). doi:10.1039/c3ra21872d.
[145] X.L. Meng, Y. Nie, J. Sun, W.G. Cheng, J.Q. Wang, H.Y. He, S.J. Zhang,
Functionalized dicyandiamide-formaldehyde polymers as efficient heterogeneous
catalysts for conversion of CO2 into organic carbonates, Green Chem. 16 (2014)
2771–2778. doi:10.1039/c3gc42331j.
[146] Y. Liu, W. Cheng, Y. Zhang, J. Sun, S. Zhang, Controllable preparation of
phosphonium-based polymeric ionic liquids as highly selective nanocatalysts for the
chemical conversion of CO2 with epoxides, Green Chem. (2017).
doi:10.1039/c7gc00444c.
[147] J.A. Castro-Osma, K.J. Lamb, M. North, Cr(salophen) Complex Catalyzed Cyclic
Carbonate Synthesis at Ambient Temperature And Pressure, ACS Catal. 6 (2016)
5012–5025. doi:10.1021/acscatal.6b01386.
[148] X.D. Lang, Y.C. Yu, L.N. He, Zn-salen complexes with multiple hydrogen bonding
donor and protic ammonium bromide: Bifunctional catalysts for CO2 fixation with
epoxides at atmospheric pressure, J. Mol. Catal. A Chem. 420 (2016) 208–215.
doi:10.1016/j.molcata.2016.04.018.
[149] W.Y. Gao, Y. Chen, Y. Niu, K. Williams, L. Cash, P.J. Perez, L. Wojtas, J. Cai, Y.S.
Chen, S. Ma, Crystal engineering of an nbo topology metal-organic framework for
chemical fixation of CO2 under ambient conditions, Angew. Chemie - Int. Ed. 53
(2014) 2615–2619. doi:10.1002/anie.201309778.
[150] H.-L. Jiang, Q. Yang, C.-C. Yang, C.-H. Lin, Metal-Organic-Framework-Derived
Hollow N-Doped Porous Carbon with Ultrahigh Concentrations of Single Zn Atoms
129 | P a g e
for Efficient Carbon Dioxide Conversion, Angew. Chemie Int. Ed. (2018).
doi:10.1002/anie.201813494.
[151] Y.H. Han, Z.Y. Zhou, C. Bin Tian, S.W. Du, A dual-walled cage MOF as an efficient
heterogeneous catalyst for the conversion of CO2under mild and co-catalyst free
conditions, Green Chem. 18 (2016) 4086–4091. doi:10.1039/c6gc00413j.
[152] X. Jiang, F. Gou, C. Qi, C2v-symmetric metalloporphyrin promoted cycloaddition of
epoxides with CO2 under atmospheric pressure, J. CO2 Util. 29 (2019) 134–139.
doi:10.1016/j.jcou.2018.12.003.
[153] Z. Dai, Q. Sun, X. Liu, C. Bian, Q. Wu, S. Pan, L. Wang, X. Meng, F. Deng, F.S.
Xiao, Metalated porous porphyrin polymers as efficient heterogeneous catalysts for
cycloaddition of epoxides with CO2 under ambient conditions, J. Catal. 338 (2016)
202–209. doi:10.1016/j.jcat.2016.03.005.
[154] X. Jiang, F. Gou, F. Chen, H. Jing, Cycloaddition of epoxides and CO2catalyzed by
bisimidazole-functionalized porphyrin cobalt(III) complexes, Green Chem. 18 (2016)
3567–3576. doi:10.1039/c6gc00370b.
[155] L. Wang, G. Zhang, K. Kodama, T. Hirose, An efficient metal- and solvent-free
organocatalytic system for chemical fixation of CO2into cyclic carbonates under mild
conditions, Green Chem. 18 (2016) 1229–1233. doi:10.1039/c5gc02697k.
[156] L. Wang, K. Kodama, T. Hirose, DBU/benzyl bromide: An efficient catalytic system
for the chemical fixation of CO2into cyclic carbonates under metal- and solvent-free
conditions, Catal. Sci. Technol. 6 (2016) 3872–3877. doi:10.1039/c5cy01892g.
[157] L. Longwitz, J. Steinbauer, A. Spannenberg, T. Werner, Calcium-Based Catalytic
System for the Synthesis of Bio-Derived Cyclic Carbonates under Mild Conditions,
ACS Catal. 8 (2018) 665–672. doi:10.1021/acscatal.7b03367.
[158] M.K. Leu, I. Vicente, J.A. Fernandes, I. de Pedro, J. Dupont, V. Sans, P. Licence,
A. Gual, I. Cano, On the real catalytically active species for CO2 fixation into cyclic
carbonates under near ambient conditions: Dissociation equilibrium of
[BMIm][Fe(NO)2Cl2] dependant on reaction temperature, Appl. Catal. B Environ.
(2019) 240–250. doi:10.1016/j.apcatb.2018.12.062.
[159] M.K. Leu, I. Vicente, J.A. Fernandes, I. de Pedro, J. Dupont, V. Sans, P. Licence,
A. Gual, I. Cano, On the real catalytically active species for CO 2 fixation into cyclic
carbonates under near ambient conditions: Dissociation equilibrium of
130 | P a g e
[BMIm][Fe(NO)2 Cl2] dependant on reaction temperature, Appl. Catal. B Environ. 245
(2019) 240–250. doi:10.1016/j.apcatb.2018.12.062.
[160] R. Babu, J.F. Kurisingal, J.S. Chang, D.W. Park, Bifunctional Pyridinium-Based
Ionic-Liquid-Immobilized Diindium Tris(diphenic acid) Bis(1,10-phenanthroline) for
CO2 Fixation, ChemSusChem. 11 (2018) 924–932. doi:10.1002/cssc.201702193.
[161] J. Peng, S. Wang, H.J. Yang, B. Ban, Z. Wei, L. Wang, B. Lei, Highly efficient fixation
of carbon dioxide to cyclic carbonates with new multi-hydroxyl bis-(quaternary
ammonium) ionic liquids as metal-free catalysts under mild conditions, Fuel. 224
(2018) 481–488. doi:10.1016/j.fuel.2018.03.119.
[162] F.D. Bobbink, D. Vasilyev, M. Hulla, S. Chamam, F. Menoud, G. Laurenczy, S.
Katsyuba, P.J. Dyson, Intricacies of Cation-Anion Combinations in Imidazolium Salt-
Catalyzed Cycloaddition of CO2 into Epoxides, ACS Catal. 8 (2018) 2589–2594.
doi:10.1021/acscatal.7b04389.
[163] X. Wang, Y. Zhou, Z. Guo, G. Chen, J. Li, Y. Shi, Y. Liu, J. Wang, Heterogeneous
conversion of CO2 into cyclic carbonates at ambient pressure catalyzed by
ionothermal-derived meso-macroporous hierarchical poly(ionic liquid)s, Chem. Sci.
6 (2015) 6916–6924. doi:10.1039/c5sc02050f.
[164] Q. Sun, Y. Jin, B. Aguila, X. Meng, S. Ma, F.S. Xiao, Porous Ionic Polymers as a
Robust and Efficient Platform for Capture and Chemical Fixation of Atmospheric CO2,
ChemSusChem. (2017). doi:10.1002/cssc.201601350.
[165] Z. Guo, Q. Jiang, Y. Shi, J. Li, X. Yang, W. Hou, Y. Zhou, J. Wang, Tethering dual
hydroxyls into mesoporous poly(ionic liquid)s for chemical fixation of CO2 at ambient
conditions: A combined experimental and theoretical study, ACS Catal. 7 (2017)
6770–6780. doi:10.1021/acscatal.7b02399.
[166] J. Hu, J. Ma, Q. Zhu, Z. Zhang, C. Wu, B. Han, Transformation of atmospheric CO2
catalyzed by protic ionic liquids: Efficient synthesis of 2-oxazolidinones, Angew.
Chemie - Int. Ed. 54 (2015) 5399–5403. doi:10.1002/anie.201411969.
[167] Y. Zhao, B. Yu, Z. Yang, H. Zhang, L. Hao, X. Gao, Z. Liu, A protic ionic liquid
catalyzes CO2 conversion at atmospheric pressure and room temperature: Synthesis
of quinazoline-2,4(1H,3H)-diones, Angew. Chemie - Int. Ed. 53 (2014) 5922–5925.
doi:10.1002/anie.201400521.
[168] Y. Wu, Y. Zhao, R. Li, B. Yu, Y. Chen, X. Liu, C. Wu, X. Luo, Z. Liu,
Tetrabutylphosphonium-Based Ionic Liquid Catalyzed CO2 Transformation at
131 | P a g e
Ambient Conditions: A Case of Synthesis of α-Alkylidene Cyclic Carbonates, ACS
Catal. 7 (2017) 6251–6255. doi:10.1021/acscatal.7b01422.
[169] J. Hu, J. Ma, H. Liu, Q. Qian, C. Xie, B. Han, Dual-ionic liquid system: An efficient
catalyst for chemical fixation of CO2 to cyclic carbonates under mild conditions,
Green Chem. 20 (2018) 2990–2994. doi:10.1039/c8gc01129j.
[170] Z. Zhang, F. Fan, H. Xing, Q. Yang, Z. Bao, Q. Ren, Efficient synthesis of cyclic
carbonates from atmospheric CO2 using a positive charge delocalized ionic liquid
catalyst, Innov. Green Process Eng. Sustain. Energy Environ. 2017 - Top. Conf. 2017
AIChE Annu. Meet. 2017–Octob (2017) 24–29.
doi:10.1021/acssuschemeng.7b00513.
[171] Y. Kumatabara, M. Okada, S. Shirakawa, Triethylamine Hydroiodide as a Simple
Yet Effective Bifunctional Catalyst for CO2Fixation Reactions with Epoxides under
Mild Conditions, ACS Sustain. Chem. Eng. 5 (2017) 7295–7301.
doi:10.1021/acssuschemeng.7b01535.
[172] T. Wang, D. Zheng, J. Zhang, B. Fan, Y. Ma, T. Ren, L. Wang, J. Zhang, Protic
Pyrazolium Ionic Liquids: An Efficient Catalyst for Conversion of CO2 in the Absence
of Metal and Solvent, ACS Sustain. Chem. Eng. 6 (2018) 2574–2582.
doi:10.1021/acssuschemeng.7b04051.
[173] L. Xiao, D. Su, C. Yue, W. Wu, Protic ionic liquids: A highly efficient catalyst for
synthesis of cyclic carbonate from carbon dioxide and epoxides, J. CO2 Util. 6 (2014)
1–6. doi:10.1016/j.jcou.2014.01.004.
[174] C.C. Tzschucke, C. Markert, W. Bannwarth, S. Roller, A. Hebel, R. Haag, Modern
separation techniques for the efficient workup in organic synthesis, Angew. Chemie
- Int. Ed. 41 (2002) 3964–4000. doi:10.1002/1521-
3773(20021104)41:21<3964::AID-ANIE3964>3.0.CO;2-3.
[175] V.K. Dloumaev, R.M. Bullock, A recyclable catalyst that precipitates at the end of
the reaction, Nature. (2003). doi:10.1038/nature01856.
[176] D.E. Bergbreiter, Using Soluble Polymers To Recover Catalysts and Ligands, Chem.
Rev. (2002). doi:10.1021/cr010343v.
[177] D. Xiong, G. Cui, J. Wang, H. Wang, Z. Li, K. Yao, S. Zhang, Reversible
Hydrophobic-Hydrophilic Transition of Ionic Liquids Driven by Carbon Dioxide,
Angew. Chemie - Int. Ed. 54 (2015) 7265–7269. doi:10.1002/anie.201500695.
132 | P a g e
[178] Y. Xiong, J. Liu, Y. Wang, H. Wang, R. Wang, One-step synthesis of
thermosensitive nanogels based on highly cross-linked poly(ionic liquid)s, Angew.
Chemie - Int. Ed. 51 (2012) 9114–9118. doi:10.1002/anie.201202957.
[179] D.J. Darensbourg, X.-B. Lu, Cobalt catalysts for the coupling of CO2 and epoxides
to provide polycarbonates and cyclic carbonates, Chem. Soc. Rev. 41 (2012) 1462.
doi:10.1039/c1cs15142h.
[180] C. Das Neves Gomes, O. Jacquet, C. Villiers, P. Thuéry, M. Ephritikhine, T. Cantat,
A diagonal approach to chemical recycling of carbon dioxide: Organocatalytic
transformation for the reductive functionalization of CO2, Angew. Chemie - Int. Ed.
51 (2012) 187–190. doi:10.1002/anie.201105516.
[181] K. Iizuka, T. Wato, Y. Miseki, K. Saito, A. Kudo, Photocatalytic reduction of carbon
dioxide over Ag cocatalyst-loaded ALa 4Ti 4O 15 (A = Ca, Sr, and Ba) using water
as a reducing reagent, J. Am. Chem. Soc. 133 (2011) 20863–20868.
doi:10.1021/ja207586e.
[182] S. Lin, C.S. Diercks, Y.B. Zhang, N. Kornienko, E.M. Nichols, Y. Zhao, A.R. Paris,
D. Kim, P. Yang, O.M. Yaghi, C.J. Chang, Covalent organic frameworks comprising
cobalt porphyrins for catalytic CO2 reduction in water, Science (80-. ). 349 (2015)
1208–1213. doi:10.1126/science.aac8343.
[183] M. Cokoja, C. Bruckmeier, B. Rieger, W.A. Herrmann, F.E. Kühn, Transformation
of carbon dioxide with homogeneous transition-metal catalysts: A molecular solution
to a global challenge?, Angew. Chemie - Int. Ed. 50 (2011) 8510–8537.
doi:10.1002/anie.201102010.
[184] D.J. Darensbourg, Making Plastics from Carbon Dioxide: Salen Metal Complexes
as Catalysts for the Production of Polycarbonates from Epoxides and CO2 , Chem.
Rev. 107 (2007) 2388–2410. doi:10.1021/cr068363q.
[185] B. Schäffner, F. Schäffner, S.P. Verevkin, A. Börner, Organic carbonates as
solvents in synthesis and catalysis, Chem. Rev. 110 (2010) 4554–4581.
doi:10.1021/cr900393d.
[186] K.I. Fujita, S. Hashimoto, M. Kanakubo, A. Oishi, Y. Taguchi, Solid-phase
intramolecular oxyselenenylation and deselenenylation reactions using polymer-
supported selenoreagents and their application to aqueous media organic synthesis,
in: Green Chem., 2003: pp. 549–553. doi:10.1039/b303915c.
133 | P a g e
[187] W. Clegg, R.W. Harrington, M. North, F. Pizzato, P. Villuendas, Cyclic carbonates
as sustainable solvents for proline-catalysed aldol reactions, Tetrahedron
Asymmetry. 21 (2010) 1262–1271. doi:10.1016/j.tetasy.2010.03.051.
[188] Q. Li, J. Chen, L. Fan, X. Kong, Y. Lu, Progress in electrolytes for rechargeable Li-
based batteries and beyond, Green Energy Environ. 1 (2016) 18–42.
doi:10.1016/j.gee.2016.04.006.
[189] L. Guo, C. Wang, X. Luo, G. Cui, H. Li, Probing catalytic activity of halide salts by
electrical conductivity in the coupling reaction of CO2 and propylene oxide, Chem.
Commun. 46 (2010) 5960–5962. doi:10.1039/c0cc00584c.
[190] B. Chatelet, L. Joucla, J.P. Dutasta, A. Martinez, K.C. Szeto, V. Dufaud,
Azaphosphatranes as structurally tunable organocatalysts for carbonate synthesis
from CO2 and epoxides, J. Am. Chem. Soc. 135 (2013) 5348–5351.
doi:10.1021/ja402053d.
[191] B.R. Buckley, A.P. Patel, K.G.U. Wijayantha, Electrosynthesis of cyclic carbonates
from epoxides and atmospheric pressure carbon dioxide, Chem. Commun. 47 (2011)
11888–11890. doi:10.1039/c1cc15467b.
[192] C. Maeda, T. Taniguchi, K. Ogawa, T. Ema, Bifunctional catalysts based on m-
phenylene-bridged porphyrin dimer and trimer platforms: Synthesis of cyclic
carbonates from carbon dioxide and epoxides, Angew. Chemie - Int. Ed. 54 (2015)
134–138. doi:10.1002/anie.201409729.
[193] T. Ema, Y. Miyazaki, J. Shimonishi, C. Maeda, J.Y. Hasegawa, Bifunctional
porphyrin catalysts for the synthesis of cyclic carbonates from epoxides and CO2:
Structural optimization and mechanistic study, J. Am. Chem. Soc. 136 (2014) 15270–
15279. doi:10.1021/ja507665a.
[194] W. Zhang, Q. Wang, H. Wu, P. Wu, M. He, A highly ordered mesoporous polymer
supported imidazolium-based ionic liquid: An efficient catalyst for cycloaddition of
CO2 with epoxides to produce cyclic carbonates, Green Chem. 16 (2014) 4767–4774.
doi:10.1039/c4gc01245c.
[195] M.H. Anthofer, M.E. Wilhelm, M. Cokoja, M. Drees, W.A. Herrmann, F.E. Kühn,
Hydroxy-functionalized imidazolium bromides as catalysts for the cycloaddition of
CO2 and epoxides to cyclic carbonates, ChemCatChem. 7 (2015) 94–98.
doi:10.1002/cctc.201402754.
134 | P a g e
[196] Y. Zhou, S. Hu, X. Ma, S. Liang, T. Jiang, B. Han, Synthesis of cyclic carbonates
from carbon dioxide and epoxides over betaine-based catalysts, J. Mol. Catal. A
Chem. 284 (2008) 52–57. doi:10.1016/j.molcata.2008.01.010.
[197] M. North, R. Pasquale, Mechanism of cyclic carbonate synthesis from epoxides and
CO2, Angew. Chemie - Int. Ed. 48 (2009) 2946–2948. doi:10.1002/anie.200805451.
[198] J. Wang, Y. Zhang, Boronic Acids as Hydrogen Bond Donor Catalysts for Efficient
Conversion of CO2 into Organic Carbonate in Water, ACS Catal. 6 (2016) 4871–
4876. doi:10.1021/acscatal.6b01422.
[199] J. Sun, L. Han, W. Cheng, J. Wang, X. Zhang, S. Zhang, Efficient acid-base
bifunctional catalysts for the fixation of CO2 with epoxides under metal- and solvent-
free conditions, ChemSusChem. 4 (2011) 502–507. doi:10.1002/cssc.201000305.
[200] J. Wang, J. Leong, Y. Zhang, Efficient fixation of CO2 into cyclic carbonates
catalysed by silicon-based main chain poly-imidazolium salts, Green Chem. 16 (2014)
4515–4519. doi:10.1039/c4gc01060d.
[201] P. Nockemann, B. Thijs, T.N. Parac-Vogt, K. Van Hecke, L. Van Meervelt, B. Tinant,
I. Hartenbach, T. Schleid, T.N. Vu, T.N. Minh, K. Binnemans, Carboxyl-functionalized
task-specific ionic liquids for solubilizing metal oxides, Inorg. Chem. 47 (2008) 9987–
9999. doi:10.1021/ic801213z.
[202] Z. Fei, D. Zhao, T.J. Geldbach, R. Scopelliti, P.J. Dyson, Brønsted acidic ionic
liquids and their zwitterions: Synthesis, characterization and pKa determination,
Chem. - A Eur. J. 10 (2004) 4886–4893. doi:10.1002/chem.200400145.
[203] X.Y. Luo, F. Ding, W.J. Lin, Y.Q. Qi, H.R. Li, C.M. Wang, Efficient and energy-saving
CO2 capture through the entropic effect induced by the intermolecular hydrogen
bonding in anion-functionalized ionic liquids, J. Phys. Chem. Lett. 5 (2014) 381–386.
doi:10.1021/jz402531n.
[204] A. Wulf, K. Fumino, R. Ludwig, Spectroscopic evidence for an enhanced anion-
cation interaction from hydrogen bonding in pure imidazolium ionic liquids, Angew.
Chemie - Int. Ed. 49 (2010) 449–453. doi:10.1002/anie.200905437.
[205] C. Bracken, P.A. Carr, J. Cavanagh, A.G. Palmer, Temperature dependence of
intramolecular dynamics of the basic leucine zipper of GCN4: Implications for the
entropy of association with DNA, J. Mol. Biol. 285 (1999) 2133–2146.
doi:10.1006/jmbi.1998.2429.
135 | P a g e
[206] S. Lin, C.S. Diercks, Y.B. Zhang, N. Kornienko, E.M. Nichols, Y. Zhao, A.R. Paris,
D. Kim, P. Yang, O.M. Yaghi, C.J. Chang, Covalent organic frameworks comprising
cobalt porphyrins for catalytic CO2 reduction in water, Science 349 (2015) 1208–1213.
doi:10.1126/science.aac8343.
[207] Q. Qian, J. Zhang, M. Cui, B. Han, Synthesis of acetic acid via methanol
hydrocarboxylation with CO2 and H2, Nat. Commun. 7 (2016) 11481.
https://doi.org/10.1038/ncomms11481.
[208] J. Qiao, Y. Liu, F. Hong, J. Zhang, A review of catalysts for the electroreduction of
carbon dioxide to produce low-carbon fuels, Chem. Soc. Rev. 43 (2014) 631–675.
doi:10.1039/c3cs60323g.
[209] N. Wei, Y. Zhang, L. Liu, Z.B. Han, D.Q. Yuan, Pentanuclear Yb(III) cluster-based
metal-organic frameworks as heterogeneous catalysts for CO2 conversion, Appl.
Catal. B Environ. 219 (2017) 603–610. doi:10.1016/j.apcatb.2017.07.085.
[210] R. Babu, S.H. Kim, J.F. Kurisingal, H.J. Kim, G.G. Choi, D.W. Park, A room
temperature synthesizable zeolitic imidazolium framework catalyst for the solvent-
free synthesis of cyclic carbonates, J. CO2 Util. 25 (2018) 6–13.
doi:10.1016/j.jcou.2018.03.006.
[211] M.H. Beyzavi, R.C. Klet, S. Tussupbayev, J. Borycz, N.A. Vermeulen, C.J. Cramer,
J.F. Stoddart, J.T. Hupp, O.K. Farha, A Hafnium-Based Metal–Organic Framework
as an Efficient and Multifunctional Catalyst for Facile CO2 Fixation and
Regioselective and Enantioretentive Epoxide Activation, J. Am. Chem. Soc. 136
(2014) 15861–15864. doi:10.1021/ja508626n.
[212] A. Barthel, Y. Saih, M. Gimenez, J.D.A. Pelletier, F.E. Kühn, V. D’Elia, J.-M. Basset,
Highly integrated CO2 capture and conversion: direct synthesis of cyclic carbonates
from industrial flue gas, Green Chem. 18 (2016) 3116–3123.
doi:10.1039/C5GC03007B.
[213] X.B. Lu, D.J. Darensbourg, Cobalt catalysts for the coupling of CO 2 and epoxides
to provide polycarbonates and cyclic carbonates, Chem. Soc. Rev. 41 (2012) 1462–
1484. doi:10.1039/c1cs15142h.
[214] Y. Zhi, P. Shao, X. Feng, H. Xia, Y. Zhang, Z. Shi, Y. Mu, X. Liu, Covalent organic
frameworks: Efficient, metal-free, heterogeneous organocatalysts for chemical
fixation of CO2 under mild conditions, J. Mater. Chem. A. 6 (2018) 374–382.
doi:10.1039/c7ta08629f.
136 | P a g e
[215] J. Li, D. Jia, Z. Guo, Y. Liu, Y. Lyu, Y. Zhou, J. Wang, Imidazolinium based porous
hypercrosslinked ionic polymers for efficient CO2capture and fixation with epoxides,
Green Chem. 19 (2017) 2675–2686. doi:10.1039/c7gc00105c.
[216] Y.A. Rulev, Z.T. Gugkaeva, A. V. Lokutova, V.I. Maleev, A.S. Peregudov, X. Wu, M.
North, Y.N. Belokon, Carbocation/Polyol Systems as Efficient Organic Catalysts for
the Preparation of Cyclic Carbonates, ChemSusChem. 10 (2017) 1152–1159.
doi:10.1002/cssc.201601246.
[217] L. Martínez-Rodríguez, J. Otalora Garmilla, A.W. Kleij, Cavitand-Based
Polyphenols as Highly Reactive Organocatalysts for the Coupling of Carbon Dioxide
and Oxiranes, ChemSusChem. 9 (2016) 749–755. doi:10.1002/cssc.201501463.
[218] C. Calabrese, L.F. Liotta, E. Carbonell, F. Giacalone, M. Gruttadauria, C. Aprile,
Imidazolium-Functionalized Carbon Nanohorns for the Conversion of Carbon
Dioxide: Unprecedented Increase of Catalytic Activity after Recycling,
ChemSusChem. 10 (2017) 1202–1209. doi:10.1002/cssc.201601427.
[219] A. Samikannu, L.J. Konwar, P. Mäki-Arvela, J.P. Mikkola, Renewable N-doped
active carbons as efficient catalysts for direct synthesis of cyclic carbonates from
epoxides and CO2, Appl. Catal. B Environ. 241 (2019) 41–51.
doi:10.1016/j.apcatb.2018.09.019.
[220] J. Zhu, T. Diao, W. Wang, X. Xu, X. Sun, S.A.C. Carabineiro, Z. Zhao, Boron doped
graphitic carbon nitride with acid-base duality for cycloaddition of carbon dioxide to
epoxide under solvent-free condition, Appl. Catal. B Environ. 219 (2017) 92–100.
doi:10.1016/j.apcatb.2017.07.041.
[221] J.K. Lee, Y.J. Kim, Y.S. Choi, H. Lee, J.S. Lee, J. Hong, E.K. Jeong, H.S. Kim, M.
Cheong, Zn-containing ionic liquids bearing dialkylphosphate ligands for the coupling
reactions of epoxides and CO2, Appl. Catal. B Environ. 111 (2012) 621–627.
doi:10.1016/j.apcatb.2011.11.015.
[222] B.-H. Xu, J.-Q. Wang, J. Sun, Y. Huang, J.-P. Zhang, X.-P. Zhang, S.-J. Zhang,
Fixation of CO2 into cyclic carbonates catalyzed by ionic liquids: a multi-scale
approach, Green Chem. 17 (2015) 108–122. doi:10.1039/C4GC01754D.
[223] J.Q. Wang, K. Dong, W.G. Cheng, J. Sun, S.J. Zhang, Insights into quaternary
ammonium salts-catalyzed fixation carbon dioxide with epoxides, Catal. Sci. Technol.
2 (2012) 1480–1484. doi:10.1039/c2cy20103h.
137 | P a g e
[224] J. Tharun, K.-M. Bhin, R. Roshan, D.W. Kim, A.C. Kathalikkattil, R. Babu, H.Y. Ahn,
Y.S. Won, D.-W. Park, Ionic liquid tethered post functionalized ZIF-90 framework for
the cycloaddition of propylene oxide and CO2, Green Chem. 18 (2016) 2479–2487.
doi:10.1039/C5GC02153G.
[225] C.K. Ng, R.W. Toh, T.T. Lin, H.K. Luo, T.S.A. Hor, J. Wu, Metal-salen molecular
cages as efficient and recyclable heterogeneous catalysts for cycloaddition of CO2
with epoxides under ambient conditions, Chem. Sci. 10 (2019) 1549–1554.
doi:10.1039/c8sc05019h.
[226] Z.A.K. Khattak, H.A. Younus, N. Ahmad, B. Yu, H. Ullah, S. Suleman, A.H. Chughtai,
B. Moosavi, C. Somboon, F. Verpoort, Mono- and dinuclear organotin(IV) complexes
for solvent free cycloaddition of CO2 to epoxides at ambient pressure, J. CO2 Util. 28
(2018) 313–318. doi:10.1016/j.jcou.2018.10.014.
[227] Y. Toda, Y. Komiyama, A. Kikuchi, H. Suga, Tetraarylphosphonium Salt-Catalyzed
Carbon Dioxide Fixation at Atmospheric Pressure for the Synthesis of Cyclic
Carbonates, ACS Catal. 6 (2016) 6906–6910. doi:10.1021/acscatal.6b02265.
[228] X. Meng, H. He, Y. Nie, X. Zhang, S. Zhang, J. Wang, Temperature-Controlled
Reaction–Separation for Conversion of CO2 to Carbonates with Functional Ionic
Liquids Catalyst, ACS Sustain. Chem. Eng. 5 (2017) 3081–3086.
doi:10.1021/acssuschemeng.6b02612.
[229] Y. Hu, C. Xie, B. Han, H. Wu, J. Song, B. Chen, Y. Yang, H. Liu, Z. Zhang,
Naturally occurring gallic acid derived multifunctional porous polymers for highly
efficient CO2 conversion and I2 capture, Green Chem. 20 (2018) 4655–4661.
doi:10.1039/c8gc02685h.
[230] Y.M. Shen, W.L. Duan, M. Shi, Chemical fixation of carbon dioxide catalyzed by
binaphthyldiamino Zn, Cu, and Co salen-type complexes, J. Org. Chem. (2003).
doi:10.1021/jo020191j.
[231] N. Liu, Y.-F. Xie, C. Wang, S.-J. Li, D. Wei, M. Li, B. Dai, Cooperative Multifunctional
Organocatalysts for Ambient Conversion of Carbon Dioxide into Cyclic Carbonates,
ACS Catal. 8 (2018) 9945–9957. doi:10.1021/acscatal.8b01925.
[232] Z. Wang, F. Gao, P. Ji, J.P. Cheng, Unexpected solvation-stabilisation of ions in a
protic ionic liquid: Insights disclosed by a bond energetic study, Chem. Sci. 9 (2018)
3538–3543. doi:10.1039/c7sc05227h.
138 | P a g e
[233] Q.W. Song, Z.H. Zhou, L.N. He, Efficient, selective and sustainable catalysis of
carbon dioxide, Green Chem. 19 (2017) 3707–3728. doi:10.1039/c7gc00199a.
[234] F.D. Bobbink, D. Vasilyev, M. Hulla, S. Chamam, F. Menoud, G. Laurenczy, S.
Katsyuba, P.J. Dyson, Intricacies of Cation–Anion Combinations in Imidazolium Salt-
Catalyzed Cycloaddition of CO2 Into Epoxides, ACS Catal. 8 (2018) 2589–2594.
doi:10.1021/acscatal.7b04389.
[235] V. Laserna, G. Fiorani, C.J. Whiteoak, E. Martin, E. Escudero-Adán, A.W. Kleij,
Carbon Dioxide as a Protecting Group: Highly Efficient and Selective Catalytic
Access to Cyclic cis-Diol Scaffolds, Angew. Chemie - Int. Ed. 53 (2014) 10416–
10419. doi:10.1002/anie.201406645.
[236] T. Wang, D. Zheng, J. Zhang, B. Fan, Y. Ma, T. Ren, L. Wang, J. Zhang, Protic
Pyrazolium Ionic Liquids: An Efficient Catalyst for Conversion of CO2 in the Absence
of Metal and Solvent, ACS Sustain. Chem. Eng. 6 (2018) 2574–2582.
doi:10.1021/acssuschemeng.7b04051.
[237] C.C. Tzschucke, C. Markert, W. Bannwarth, S. Roller, A. Hebel, R. Haag, Modern
separation techniques for the efficient workup in organic synthesis, Angew. Chemie
- Int. Ed. (2002). doi:10.1002/1521-3773(20021104)41:21<3964::AID-
ANIE3964>3.0.CO;2-3.
[238] Y. Zhang, B. Wang, E.H.M. Elageed, L. Qin, B. Ni, X. Liu, G. Gao, Swelling
Poly(ionic liquid)s: Synthesis and Application as Quasi-Homogeneous Catalysts in
the Reaction of Ethylene Carbonate with Aniline, ACS Macro Lett. 5 (2016) 435–438.
doi:10.1021/acsmacrolett.6b00178.
[239] Y. Zhang, Y. Zhang, B. Chen, L. Qin, G. Gao, Swelling Poly (Ionic Liquid)s:
Heterogeneous Catalysts That are Superior than Homogeneous Catalyst for
Ethylene Carbonate Transformation, ChemistrySelect. 2 (2017) 9443–9449.
doi:10.1002/slct.201702081.
[240] T. Song, J. Deng, L. Deng, L. Bai, X. Zhang, S. Zhang, P. Szabo, A.E. Daugaard,
Poly(vinylimidazole-co-butyl acrylate) membranes for CO2 separation, Polymer
(Guildf). 160 (2019) 223–230. doi:10.1016/j.polymer.2018.11.058.
139 | P a g e
APPENDICES
The Cartesian coordinates for Chapter 2
C -
3.060394 -
2.010603 -
0.289510
A
C -
3.730399 -
0.878540 0.087082
C -
3.094583 0.400197 0.005711
C -
1.775153 0.406921
-0.528234
C -
1.171430 -
0.762297 -
0.881929
N -
1.791046 -
1.974263 -
0.764201
H -
1.165493 1.309452
-0.622426
H -
0.156713 -
0.775514 -
1.257683
C -
1.063810 -
3.221696 -
1.095193
H -
0.247143 -
2.944732 -
1.756378
H -
1.751377 -
3.869912 -
1.642896
C -
0.512175 -
3.956418 0.136807
H -
1.341489 -
4.399277 0.698996
H 0.083741 -
4.791413 -
0.244424
C 0.326805 -
3.118631 1.107816
H -
0.269769 -
2.312796 1.550098
H 0.642031 -
3.736616 1.952656
H -
3.519447 -
2.988727 -
0.227657
H -
4.742095 -
0.988023 0.447740
Br 0.674035 2.794755 -
0.296957
C 1.566110 -
2.465929 0.516085
O 1.799771 -
2.417869 -
0.678870
O 2.327959 -
1.934377 1.454464
H 3.081139 -
1.394207 1.056242
140 | P a g e
N -
3.711330 1.523442 0.413708
C -
5.095833 1.477991 0.879179
H -
5.402854 2.484849 1.152116
H -
5.772622 1.114657 0.098338
H -
5.198470 0.839737 1.762260
C -
3.092125 2.854848 0.305568
H -
3.447585 3.368872
-0.593560
H -
3.375142 3.438844 1.182333
H -
2.002575 2.803670 0.272862
C 3.952659 0.914970 0.016438
H 2.887619 1.141542 0.005955
C 4.428360 -
0.151681 -
0.868735
H 5.465475 -
0.156104 -
1.192899
H 3.725148 -
0.681837 -
1.503278
O 4.265292 -
0.418435 0.547486
C 4.842290 2.026140 0.491094
H 4.695148 2.901622 -
0.147131
H 4.576748 2.315311 1.510903
H 5.895015 1.733749 0.467078
C 2.707337 -
1.010979 2.188519
C 3.401140 -
0.999323 1.008506
C 2.916681 -
0.248902 -
0.106401
C 1.726257 0.496303 0.114883
C 1.088200 0.435300 1.320891
N 1.558263 -
0.313966 2.356867
H 1.250611 1.091440 -
0.659400
H 0.154702 0.948526 1.501352
C 0.801559 -
0.379292 3.635030
H 0.085668 0.435773 3.605405
141 | P a g e
H 1.514929 -
0.200904 4.443639
TS1
C 0.061867 -
1.707982 3.859823
H 0.780783 -
2.480171 4.158203
H -
0.582819 -
1.542598 4.729230
C -
0.770681 -
2.255217 2.691786
H -
0.111929 -
2.578369 1.876052
H -
1.290334 -
3.160962 3.013053
H 3.050277 -
1.579456 3.043097
H 4.312577 -
1.574948 0.951722
Br -
0.655834 1.735319
-2.297717
C -
1.801838 -
1.312029 2.052437
O -
1.727921 -
0.087940 2.239447
O -
2.643296 -
1.911034 1.295031
H -
3.346846 -
1.178107 0.475511
N 3.550169 -
0.250554 -
1.295824
C 4.824295 -
0.948745 -
1.452246
H 5.153387 -
0.848773 -
2.483728
H 5.600120 -
0.527189 -
0.803322
H 4.720507 -
2.015196 -
1.232108
C 3.078713 0.578142 -
2.415756
H 3.448080 1.605676 -
2.329055
H 3.450008 0.147322 -
3.344428
H 1.989664 0.605352 -
2.466226
C -
2.953194 -
0.663197 -
1.510847
H -
2.164952 -
1.402213 -
1.372486
C -
2.715049 0.623900
-0.881511
H -
3.331880 1.466811
-1.149807
1.77 Å
142 | P a g e
H -
2.056718 0.708102
-0.034691
O -
3.858719 -
0.631937 -
0.373485
C -
3.638837 -
0.746330 -
2.847249
H -
2.917452 -
0.521337 -
3.636131
H -
4.042805 -
1.749170 -
3.006067
H -
4.457204 -
0.025477 -
2.906485
143 | P a g e
C -
3.453871 -
1.376485 -
0.302415
B
C -
3.914550 -
0.175100 0.166678
C -
3.059308 0.964465 0.176818
C -
1.749384 0.766046
-0.330419
C -
1.354069 -
0.464794 -
0.784862
N -
2.195227 -
1.531482 -
0.774632
H -
1.013539 1.556409
-0.361294
H -
0.343165 -
0.681242 -
1.117581
C -
1.711123 -
2.865227 -
1.235550
H -
0.862999 -
2.674660 -
1.886389
H -
2.525973 -
3.315000 -
1.807922
C -
1.276772 -
3.785592 -
0.086579
H -
2.165849 -
4.137398 0.452574
H -
0.842023 -
4.668893 -
0.566925
C -
0.279326 -
3.204675 0.927379
H -
0.757667 -
2.397567 1.498586
H -
0.032841 -
3.973458 1.662553
H -
4.080725 -
2.258386 -
0.317904
H -
4.931792 -
0.124684 0.524373
Br 1.923407 2.068754 -
0.915841
C 1.049805 -
2.618011 0.380262
O 1.034276 -
2.138668 -
0.788770
O 2.004990 -
2.618645 1.186535
H 3.434741 -
1.651803 0.979749
N -
3.470215 2.164531 0.644436
C -
4.823406 2.333649 1.170095
H -
4.949563 3.363007 1.496358
144 | P a g e
H -
5.578170 2.125266 0.405110
H -
5.002422 1.680527 2.030117
C -
2.551659 3.306473 0.644832
H -
2.235022 3.560404
-0.370785
H -
3.061163 4.167819 1.069868
H -
1.662532 3.100029 1.246779
C 3.527156 0.300528 0.855834
H 2.635298 0.340263 1.496719
C 3.084647 0.440513 -
0.602932
H 3.928315 0.580058 -
1.275918
H 2.462646 -
0.399090 -
0.907443
O 4.148380 -
0.965898 0.953874
C 4.524826 1.361649 1.298848
H 4.108014 2.367069 1.203901
H 4.804893 1.191626 2.340637
H 5.431421 1.297046 0.689637
145 | P a g e
C 3.556574 1.956731 -0.740973
C
C 4.337966 0.834433 -0.731459
C 3.738374 -0.456011 -0.647366
C 2.320230 -0.483606 -0.593516
C 1.601150 0.682282 -0.614614
N 2.204501 1.897670 -0.687941
H 1.763520 -1.404411 -0.501153
H 0.521435 0.676052 -0.553835
C 1.402447 3.154412 -0.635630
H 0.382753 2.888184 -0.904783
H 1.812833 3.827121 -1.391946
C 1.391519 3.809818 0.752821
H 2.362121 4.278316 0.957269
H 0.656123 4.615863 0.684534
C 1.019575 2.855361 1.898422
H 1.866195 2.221897 2.176986
H 0.772021 3.446426 2.785901
H 3.986341 2.948266 -0.792568
H 5.408835 0.960248 -0.780650
Br 4.814366 0.173082 -1.285966
C 0.188980 1.940509 1.574240
O 1.069994 2.409644 0.819804
O 0.139223 0.773669 2.056249
H 0.935389 -0.401310 1.161035
N 4.480434 -1.584197 -0.620332
C 5.938556 -1.515051 -0.688448
H 6.352480 -0.960076 0.159446
H 6.341199 -2.524409 -0.659320
H 6.273889 -1.042593 -1.617402
C 3.828113 -2.894472 -0.530361
H 3.196882 -3.082497 -1.403720
H 4.594308 -3.664868 -0.487734
H 3.208528 -2.969175 0.364837
C 2.675632 -0.991667 0.374305
H 3.010929 -1.941798 -0.053527
C 2.924092 0.120433 -0.647650
H 2.704441 1.104081 -0.236425
H 2.341345 -0.059321 -1.548147
O 1.257408 -1.104179 0.528144
C 3.371815 -0.760569 1.712634
H 4.455280 -0.709477 1.584345
H 3.141115 -1.581666 2.395084
H 3.026100 0.173364 2.162522
C 0.389430 -3.656972 0.932226
O 0.685892 -3.406609 0.560556
O 1.429759 -4.000547 1.307521
146 | P a g e
C -
0.433256 0.183308 0.531999
TS2
C -
0.700601 1.311320 1.255354
C -
0.115650 2.559590 0.887116
C 0.694556 2.542086 -
0.281213
C 0.935784 1.371976 -
0.942352
N 0.384796 0.192991 -
0.549452
H 1.199709 3.430524 -
0.626793
H 1.618468 1.315231 -
1.776321
C 0.716632 -
1.063416 -
1.272985
H 1.367987 -
0.767829 -
2.088510
H -
0.215064 -
1.461980 -
1.684308
C 1.425711 -
2.128237 -
0.414899
H 0.681285 -
2.719766 0.130133
H 1.888742 -
2.814492 -
1.130691
C 2.473973 -
1.629083 0.588856
H 1.991847 -
1.167997 1.457524
H 3.021664 -
2.484890 0.993314
H -
0.854157 -
0.776118 0.801277
H -
1.341924 1.220991 2.118449
Br 6.810359 3.351181 -
2.457945
C 3.502201 -
0.603390 0.089249
O 3.439337 -
0.163231 -
1.069075
O 4.339407 -
0.252872 0.991754
H 4.703873 0.967908 0.993520
N -
0.313924 3.680878 1.600838
C -
1.001631 3.619743 2.890386
H -
0.465597 2.972039 3.591059
147 | P a g e
H -
1.044101 4.620143 3.313379
H -
2.027726 3.258508 2.776032
C 0.357270 4.931119 1.219937
H 0.090344 5.210988 0.197620
H 0.016001 5.723039 1.882422
H 1.444501 4.843167 1.300054
C 6.018847 2.564179 0.255824
H 6.170495 3.611619 0.524703
C 5.533794 2.495667 -
1.193182
H 5.393985 1.474627 -
1.539172
H 4.615800 3.063583 -
1.308488
O 4.959120 2.079801 1.096171
C 7.279430 1.754521 0.539763
H 8.116557 2.126820 -
0.053661
H 7.536453 1.834485 1.597894
H 7.123879 0.699023 0.301973
C 3.599922 3.112838 1.488426
O 3.793477 4.195875 1.006370
O 2.841165 2.440811 2.125742
C 3.920704 0.908221 -0.635684
D
C 4.150917 -0.394807 -0.294909
C 3.138778 -1.382943 -0.494151
C 1.961218 -0.938533 -1.159136
C 1.800175 0.376710 -1.470790
N 2.753411 1.313748 -1.195132
H 1.132344 -1.606467 -1.340031
H 0.882031 0.751981 -1.896588
C 2.482115 2.749352 -1.446979
H 1.525140 2.787416 -1.957853
H 3.253589 3.124926 -2.124613
C 2.426773 3.622465 -0.177074
H 3.442608 3.903451 0.120190
H 1.932910 4.552206 -0.475852
C 1.729889 3.027163 1.052406
H 2.319260 2.210766 1.483533
H 1.667639 3.780762 1.842754
H 4.658865 1.679339 -0.458394
H 5.094903 -0.637321 0.168671
Br 4.738985 -0.376885 -1.126189
C 0.344578 2.445811 0.835030
O 0.176047 2.335128 -0.260692
O 0.189419 2.035124 1.972548
H 0.807710 1.264731 1.808443
N 3.284583 -2.649286 -0.079832
C 4.515618 -3.077214 0.579976
H 4.480531 -4.154763 0.720981
148 | P a g e
H 5.393973 -2.847275 -0.029702
H 4.626585 -2.603530 1.561437
C 2.178194 -3.614164 -0.190046
H 2.122773 -4.027234 -1.203448
H 2.364736 -4.429066 0.506815
H 1.225016 -3.149192 0.074062
C 2.798486 -0.538649 1.072334
H 2.926730 -1.621044 1.025025
C 2.961097 0.038012 -0.332906
H 2.874534 1.122047 -0.346931
H 2.243852 -0.417232 -1.007569
O 1.445069 -0.266269 1.487449
C 3.720915 0.075430 2.115682
H 4.765910 -0.120540 1.869199
H 3.505913 -0.353424 3.096450
H 3.578713 1.158880 2.174777
C 0.378188 -1.173122 1.040920
O 0.727887 -2.079173 0.271132
O 0.718088 -0.846319 1.499810
149 | P a g e
C 0.531328 0.781110 0.075689
TS3
C 0.100118 1.832824 0.835866
C 0.733679 3.109434 0.730774
C 1.782383 3.204723 -
0.226860
C 2.161697 2.108940 -
0.947747
N 1.556394 0.896812 -
0.804920
H 2.332843 4.122023 -
0.407460
H 2.979220 2.152688 -
1.653757
C 2.028229 -0.276555 -
1.585315
H 2.701692 0.112821 -
2.342770
H 1.158313 -0.714900 -
2.079789
C 2.755320 -1.337510 -
0.741808
H 2.024108 -1.939716 -
0.192237
H 3.230608 -2.013651 -
1.458625
C 3.793536 -0.820605 0.259858
H 3.312612 -0.303771 1.097153
H 4.316335 -1.665912 0.716161
H 0.069089 -0.194833 0.144366
H 0.724355 1.663361 1.511597
Br 4.304292 5.784168 -
0.859201
C 4.844152 0.128889 -
0.299474
O 4.869883 0.495695 -
1.461004
O 5.673685 0.514998 0.646821
H 6.295019 1.246055 0.368272
N 0.359075 4.153292 1.492144
C 0.777607 4.033641 2.405624
H 0.902835 4.976241 2.932404
H 1.706297 3.816807 1.867363
H 0.605081 3.250321 3.149030
C 0.975587 5.478889 1.336385
H 0.511864 6.036635 0.516240
H 0.841613 6.034598 2.262687
H 2.043620 5.403160 1.138650
C 6.968586 3.957563 -
0.346638
H 7.930941 4.478391 -
0.395015
C 6.058023 4.833554 0.505365
H 5.306196 4.363603 1.113324
H 6.356347 5.831067 0.770106
150 | P a g e
O 7.174421 2.734140 0.380156
C 6.548127 3.590080 -
1.761427
H 6.453760 4.485212 -
2.374932
H 7.314884 2.939180 -
2.187704
H 5.598720 3.056317 -
1.775021
C 7.543168 2.995242 1.776244
O 7.361429 4.206211 2.077428
O 7.928431 2.026920 2.392815
151 | P a g e
C 3.792659 1.486510 -0.150250
E
C 4.164214 0.279228 0.374444
C 3.290355 -0.851250 0.287494
C 2.061601 -0.634170 -0.399610
C 1.762353 0.597307 -0.898480
N 2.604570 1.666964 -0.778320
H 1.303609 -1.408890 -0.545480
H 0.826304 0.777509 -1.410520
C 2.200764 3.001357 -1.280000
H 1.384467 2.839207 -1.979310
H 3.046260 3.420394 -1.829950
C 1.757247 3.969792 -0.171810
H 2.631909 4.306688 0.394508
H 1.356333 4.853110 -0.677460
C 0.728652 3.424079 0.822286
H 1.139868 2.596156 1.408590
H 0.478207 4.195279 1.556817
H 4.437187 2.353743 -0.088690
H 5.130280 0.213933 0.851949
Br 0.652219 -2.734780 -0.865700
C 0.571767 2.935845 0.208779
O 0.822013 2.958029 -0.978780
O 1.386306 2.461724 1.145492
H 2.180162 2.037198 0.752069
N 3.621781 -2.037460 0.824121
C 4.911325 -2.214690 1.489605
H 4.973499 -3.237510 1.854111
H 5.745365 -2.046590 0.800532
H 5.014692 -1.540790 2.345675
C 2.765990 -3.232820 0.753517
H 3.244409 -3.990380 0.125798
H 2.639706 -3.635490 1.761228
H 1.777856 -3.020990 0.345991
C 3.996320 0.058081 -0.787460
H 4.960954 0.506735 -1.048110
C 4.181607 -1.342930 -0.204720
H 3.269011 -1.941970 -0.276560
H 5.034895 -1.878590 -0.616880
O 3.530038 0.786356 0.397138
C 3.010320 0.176098 -1.926140
H 3.430863 -0.309640 -2.811780
H 2.822224 1.224531 -2.165570
H 2.074674 -0.331500 -1.682030
C 3.947413 0.123470 1.524145
O 4.455470 -1.073610 1.195284
O 3.866219 0.576627 2.623750
152 | P a g e
C -8.511981 -
0.453947 0.340229
C -9.639057 0.158980 -0.163410
C -
10.113374 -
0.151590 -1.453109
C -9.336851 -
1.084072 -2.205695
C -8.204012 -
1.622617 -1.665090
N -7.764283 -
1.295156 -0.425897
H -9.628319 -
1.399758 -3.195441
H -7.605935 -
2.342931 -2.206381
C -6.612734 -
1.994012 0.194365
H -6.288222 -
2.757778 -0.514888
H -7.019623 -
2.487888 1.085168
C -5.458873 -
1.060856 0.558219
H -5.791049 -
0.316993 1.286819
H -4.708780 -
1.660813 1.080026
C -4.822950 -
0.368186 -0.646654
H -4.443329 -
1.099213 -1.370464
H -5.549829 0.239463 -1.195895
H -8.144909 -
0.244271 1.330042
H -
10.181292 0.815001 0.498992
Br -9.337071 -
2.412184 2.439486
C -3.666599 0.536030 -0.279799
O -3.217559 0.673535 0.836378
O -3.183232 1.180635 -1.354830
H -2.438503 1.749857 -1.076648
N -
11.250466 0.394123 -1.956391
C -
12.082180 1.251388 -1.113003
H -
12.432370 0.718574 -0.223276
H -
11.533230 2.142848 -0.794795
H -
12.949465 1.575097 -1.684013
C -
11.739295 0.007300 -3.276574
153 | P a g e
H -
10.983261 0.188036 -4.045934
H -
12.032119 -
1.048234 -3.310301
H -
12.611433 0.609879 -3.520525
C -0.935544 2.956535 1.156327
C 0.574825 2.978096 1.392828
C 0.126613 3.204258 -0.868869
H -1.456308 2.114653 1.605945
H -1.412713 3.897617 1.441269
H 0.978292 1.974065 1.535245
C 1.051562 3.909107 2.482747
H 0.631330 3.588821 3.440539
H 2.137861 3.871396 2.563655
H 0.732927 4.935945 2.287743
O 1.065285 3.430246 0.083962
O -1.041147 2.822456 -0.285115
O 0.296131 3.318041 -2.040182
C 7.959520 -
1.134208 0.035742
C 8.306178 -
1.955771 -1.014799
C 9.112273 -
1.478290 -2.067068
C 9.492384 -
0.103542 -1.999809
C 9.075804 0.670063 -0.954010
N 8.288696 0.186753 0.037500
H 10.124364 0.349230 -2.748006
H 9.361740 1.709607 -0.869760
C 7.962316 1.000427 1.232885
H 8.516266 1.936465 1.139506
H 8.367231 0.437577 2.082752
C 6.466230 1.263638 1.398925
H 5.925707 0.319209 1.500201
H 6.332011 1.778286 2.354196
C 5.859384 2.096500 0.270517
H 6.362771 3.065419 0.173808
H 5.978409 1.605142 -0.701438
H 7.363566 -
1.485850 0.860335
H 8.011188 -
2.990985 -0.948894
Br 9.544305 -
1.941510 2.438407
C 4.382678 2.372608 0.450725
O 3.703286 1.965892 1.366820
O 3.899189 3.138143 -0.541783
H 2.943100 3.280094 -0.394039
N 9.518669 -
2.277549 -3.086941
C 9.203023 -
3.704892 -3.064167
154 | P a g e
H 9.644856 -
4.199853 -2.193302
H 8.121353 -
3.867371 -3.048698
H 9.600622 -
4.169498 -3.963700
C 10.411876 -
1.763815 -4.121379
H 9.974295 -
0.898320 -4.627215
H 11.387157 -
1.477526 -3.711862
H 10.571220 -
2.539267 -4.867350
C 4.506058 -3.219033 -1.566193
C 5.343730 -2.363416 -2.241861
C 5.861189 -1.182477 -1.622969
C 5.393530 -0.914745 -0.295968
C 4.573122 -1.818891 0.336783
N 4.144364 -2.975877 -0.268548
H 5.625685 -0.002284 0.254167
H 4.220190 -1.620784 1.340075
C 3.328228 -4.026964 0.434711
H 4.029469 -4.739104 0.886867
H 2.794454 -4.563373 -0.361554
C 2.361368 -3.474088 1.487089
H 2.041522 -2.466343 1.196994
H 1.461289 -4.096824 1.486306
C 2.935533 -3.459175 2.937923
H 2.765941 -4.426513 3.416754
H 4.013368 -3.268791 2.921433
H 4.033274 -4.084886 -2.033415
H 5.591379 -2.620030 -3.261333
Br 2.238476 -5.676048 -2.457503
C 2.286084 -2.372761 3.755588
O 1.351875 -2.544928 4.569495
O 2.791261 -1.166232 3.457187
H 2.305209 -0.365070 3.833507
N 6.730283 -0.376631 -2.292963
C 7.190253 -0.760079 -3.637610
H 7.714001 -1.724373 -3.627297
H 6.354608 -0.825296 -4.344251
H 7.882171 0.001227 -3.996826
C 7.415885 0.789564 -1.699784
H 6.932510 1.181686 -0.801264
H 8.449579 0.526394 -1.439374
H 7.438718 1.594765 -2.441379
C 3.647037 3.927709 -0.158921
C 3.097383 3.954896 -1.421121
C 1.911881 4.700689 -1.696119
C 1.354800 5.433720 -0.602934
C 1.964626 5.396865 0.624355
155 | P a g e
N 3.092608 4.651685 0.860956
H 0.406282 5.953860 -0.680250
H 1.560538 5.944240 1.465078
C 3.658795 4.535198 2.242871
H 3.429246 5.471071 2.761316
H 4.740946 4.422415 2.143044
C 3.113174 3.305108 2.988460
H 3.447988 2.413700 2.445807
H 3.623428 3.253529 3.957220
C 1.589824 3.339798 3.185956
H 1.320811 4.017998 4.009889
H 1.066357 3.719815 2.303869
H 4.511722 3.314534 0.115577
H 3.582706 3.366781 -2.186627
Br 6.137690 2.126657 1.328024
C 0.975859 1.994971 3.483333
O 1.591182 1.045267 4.009232
O 0.310932 1.948004 3.118982
H 0.831134 1.080868 3.220601
N 1.341988 4.713091 -2.931171
C 2.003052 4.031990 -4.051057
H 3.021764 4.408690 -4.206762
H 2.056768 2.947861 -3.887057
H 1.431121 4.213760 -4.960344
C 0.102920 5.475870 -3.198165
H 0.642537 5.335817 -2.404810
H 0.312153 6.549629 -3.291724
H 0.323891 5.121309 -4.137927
C 2.999930 -2.527497 -1.139850
C 2.092085 -1.908530 -1.967843
C 0.911462 -2.577789 -2.416936
C 0.737185 -3.922758 -1.959518
C 1.688122 -4.492840 -1.151129
N 2.808163 -3.818693 -0.730143
H 0.145650 -4.525277 -2.176793
H 1.584183 -5.514221 -0.809220
C 3.782229 -4.448827 0.218281
H 3.777677 -5.523948 0.015603
H 4.766540 -4.027888 -0.007044
C 3.464104 -4.129414 1.690006
H 3.529411 -3.044753 1.817210
H 4.282808 -4.536286 2.295198
C 2.113881 -4.677865 2.173604
H 2.174289 -5.754093 2.389955
H 1.341438 -4.577308 1.402678
H 3.912166 -2.044982 -0.777212
H 2.309346 -0.892617 -2.263151
Br 5.966739 -1.643432 0.303463
C 1.555936 -3.992581 3.399563
O 2.173347 -3.197525 4.132633
O 0.270479 -4.331486 3.618138
H 0.236788 -3.727483 4.253742
N 0.020927 -1.949266 -3.231831
C 0.281561 -0.570687 -3.672395
156 | P a g e
H 1.182976 -0.505713 -4.296353
H 0.397776 0.105499 -2.818045
H 0.568455 -0.231516 -4.264359
C 1.148617 -2.606944 -3.848631
H 1.445776 -3.538484 -3.357660
H 0.942692 -2.830068 -4.904022
H 2.001822 -1.922493 -3.795302
C 4.414243 3.040106 -0.996106
C 4.913324 2.440992 -2.133696
C 5.975921 1.494154 -2.052844
C 6.585006 1.332439 -0.773912
C 6.074444 1.980131 0.316942
N 4.966195 2.778780 0.228187
H 7.411913 0.658215 -0.625332
H 6.495136 1.843273 1.302324
C 4.278721 3.233388 1.474979
H 5.054900 3.535662 2.185611
H 3.673787 4.106720 1.205207
C 3.369768 2.136814 2.059326
H 2.619108 1.868107 1.307023
H 2.807056 2.599172 2.878567
C 4.089117 0.873821 2.564215
H 4.854618 1.118906 3.313491
H 4.623284 0.317561 1.771648
H 3.585282 3.753363 -1.003610
H 4.440994 2.678226 -3.076562
Br 2.147654 5.594193 -0.370699
C 3.158023 -0.134457 3.186860
O 1.904716 -0.067307 3.189636
O 3.804582 -1.178515 3.720652
H 3.198389 -1.932754 4.002119
N 6.392366 0.761824 -3.122148
C 5.879358 1.040780 -4.466995
H 5.935000 2.110743 -4.693050
H 4.837086 0.711990 -4.588044
H 6.494133 0.511185 -5.195302
C 7.261341 -0.419024 -2.919337
H 6.926233 -0.977438 -2.035101
H 8.313492 -0.130903 -2.799002
H 7.178253 -1.066209 -3.794211
157 | P a g e
The Cartesian coordinates for Chapter 3
C 0.952 -1.92 -2.215
O 1.694 -1.65 0.033
H 1.892 -1.489 -2.564
H 0.537 -2.59 -2.967
Br -0.325 -0.374 -2.158
C 1.111 -2.564 -0.845
H 0.112 -2.861 -0.485
C 1.975 -3.829 -0.992
H 1.511 -4.577 -1.645
H 2.961 -3.574 -1.394
H 2.113 -4.271 -0.002
C -2.67 1.472 -0.126
C -2.846 0.021 0.256
H -1.61 1.711 -0.135
H -3.012 1.604 -1.157
N -3.96 -0.601 -0.16
C -4.126 -2.067 -0.096
H -4.496 -2.396 -1.074
H -4.888 -2.305 0.654
C -2.804 -2.736 0.239
H -2.972 -3.786 0.494
H -2.13 -2.701 -0.624
C -2.161 -2.003 1.409
H -2.82 -2.023 2.287
H -1.186 -2.403 1.696
N -1.948 -0.587 1.029
C -0.703 0.118 1.426
H -0.989 1.123 1.742
H -0.064 0.168 0.544
C 0.122 -0.535 2.565
C 1.259 0.479 2.962
H 0.887 1.498 3.104
H 1.654 0.15 3.924
N 2.414 0.464 2.031
C 3.446 -0.538 2.394
H 3.631 -0.424 3.465
H 3.025 -1.531 2.227
C 4.724 -0.307 1.606
H 5.417 -1.134 1.784
H 5.216 0.615 1.937
158 | P a g e
C 4.395 -0.216 0.126
H 5.273 0.094 -0.447
H 4.019 -1.171 -0.255
N 3.351 0.8 -0.088
C 2.442 1.087 0.847
C 1.505 2.243 0.565
H 0.854 1.978 -0.275
H 0.858 2.39 1.424
C 2.239 3.575 0.266
H 3.111 3.669 0.925
H 1.558 4.389 0.537
C 2.654 3.754 -1.201
H 3.067 4.76 -1.335
H 1.753 3.703 -1.827
C 3.666 2.718 -1.703
H 4.637 2.86 -1.212
H 3.83 2.865 -2.776
C 3.207 1.273 -1.483
H 2.171 1.126 -1.803
H 3.814 0.593 -2.084
C -5.141 0.162 -0.622
H -5.907 -0.588 -0.826
H -4.925 0.653 -1.58
C -5.677 1.167 0.413
H -6.728 1.359 0.167
H -5.67 0.687 1.4
C -4.938 2.513 0.461
H -5.036 3 -0.519
H -5.44 3.169 1.181
C -3.448 2.422 0.815
H -3.321 2.089 1.854
H -3.002 3.42 0.748
H -0.529 -0.564 3.467
O 0.621 -1.763 2.248
H 1.24 -1.74 1.013
159 | P a g e
C 0.288 -0.747 -2.915
O 1.26 -1.587 -0.901
H 1.292 -0.619 -3.32
H -0.433 -0.911 -3.715
Br -0.206 1.038 -2.155
C 0.244 -1.817 -1.837
H -0.741 -1.751 -1.347
C 0.365 -3.202 -2.491
H -0.457 -3.403 -3.188
H 1.314 -3.291 -3.031
H 0.352 -3.962 -1.705
C -2.491 1.556 0.387
C -2.819 0.081 0.378
H -1.421 1.686 0.51
H -2.735 1.984 -0.588
N -4.004 -0.288 -0.136
C -4.445 -1.695 -0.203
H -4.942 -1.837 -1.168
H -5.192 -1.865 0.583
C -3.267 -2.64 -0.053
H -3.627 -3.66 0.104
H -2.663 -2.641 -0.966
C -2.407 -2.209 1.124
H -2.963 -2.292 2.067
H -1.49 -2.801 1.179
N -1.993 -0.793 0.954
C -0.664 -0.351 1.47
H -0.832 0.456 2.191
H -0.092 0.02 0.617
C 0.165 -1.481 2.137
C 1.46 -0.86 2.775
H 1.272 0.081 3.298
H 1.817 -1.569 3.522
N 2.57 -0.719 1.804
C 3.39 -1.95 1.679
H 3.626 -2.273 2.697
H 2.764 -2.718 1.219
C 4.664 -1.682 0.897
H 5.165 -2.63 0.683
H 5.354 -1.065 1.484
C 4.311 -0.972 -0.398
H 5.215 -0.659 -0.927
H 3.706 -1.609 -1.052
160 | P a g e
N 3.529 0.239 -0.101
C 2.695 0.295 0.94
C 1.973 1.601 1.184
H 1.326 1.813 0.327
H 1.32 1.495 2.044
C 2.938 2.79 1.437
H 3.774 2.451 2.061
H 2.392 3.532 2.03
C 3.459 3.469 0.164
H 4.061 4.34 0.445
H 2.6 3.855 -0.402
C 4.282 2.556 -0.754
H 5.23 2.281 -0.276
H 4.536 3.105 -1.668
C 3.536 1.279 -1.154
H 2.507 1.495 -1.454
H 4.015 0.816 -2.019
C -5.041 0.707 -0.502
H -5.854 0.129 -0.945
H -4.663 1.364 -1.293
C -5.577 1.518 0.688
H -6.561 1.909 0.407
H -5.741 0.835 1.532
C -4.684 2.693 1.11
H -4.632 3.409 0.278
H -5.159 3.224 1.943
C -3.255 2.305 1.508
H -3.262 1.693 2.419
H -2.695 3.214 1.749
H -0.418 -1.825 3.021
O 0.459 -2.497 1.275
H 0.953 -2.008 0.016
161 | P a g e
C 1.094 -2.525 -1.953
O 1.585 -1.971 0.011
H 1.859 -1.991 -2.504
H 0.162 -2.715 -2.467
Br -0.353 -0.191 -2.101
C 1.481 -3.18 -0.694
H 0.67 -3.828 -0.311
C 2.771 -3.998 -0.749
H 2.646 -4.925 -1.321
H 3.582 -3.415 -1.198
H 3.059 -4.261 0.276
C -2.76 1.548 -0.061
C -2.898 0.069 0.207
H -1.706 1.81 -0.077
H -3.096 1.723 -1.087
N -4.037 -0.524 -0.171
C -4.199 -1.978 -0.012
H -4.951 -2.311 -0.729
H -4.566 -2.202 0.999
C -2.855 -2.638 -0.274
H -2.93 -3.722 -0.155
H -2.546 -2.421 -1.302
C -1.826 -2.092 0.7
H -1.906 -2.543 1.69
H -0.821 -2.274 0.324
N -1.935 -0.615 0.839
C -0.697 0.066 1.262
H -0.953 1.097 1.492
H -0.02 0.035 0.405
C 0.027 -0.482 2.501
C 1.202 0.485 2.847
H 0.849 1.511 2.972
H 1.605 0.168 3.81
N 2.328 0.421 1.889
C 3.355 -0.594 2.232
H 3.54 -0.509 3.305
H 2.95 -1.586 2.026
C 4.627 -0.351 1.44
H 5.329 -1.171 1.615
H 5.111 0.579 1.762
162 | P a g e
C 4.274 -0.273 -0.034
H 5.141 0.021 -0.631
H 3.88 -1.228 -0.394
N 3.232 0.745 -0.243
C 2.35 1.057 0.703
C 1.445 2.243 0.441
H 0.794 2.011 -0.41
H 0.797 2.392 1.299
C 2.225 3.559 0.19
H 3.083 3.613 0.873
H 1.56 4.385 0.466
C 2.68 3.765 -1.261
H 3.137 4.756 -1.353
H 1.792 3.77 -1.908
C 3.659 2.703 -1.775
H 4.623 2.784 -1.257
H 3.856 2.882 -2.838
C 3.126 1.276 -1.625
H 2.087 1.183 -1.957
H 3.706 0.587 -2.242
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H 0.651 -0.588 -0.757
C 1.673 -1.888 1.792
O 2.783 -2.242 1.682
O 0.563 -1.568 1.969
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Abbreviation list
ABBCs Carboxylic acid–base bifunctional catalysts
ABMDFP Ammonium bromide modified polyquaternium ionic
liquids
AIBN N-vinylimidazole, azodiisobutyronitrile
[bmim]Br 1-Butyl-3-methylimidazolium Bromide
[bmim]Cl 1-Butyl-3-methylimidazolium chloride
BmimOAc 1-butyl-3-methyl-imidazolium acetate
[BPy]Br Butylpyridinium bromide
BrC2COOH 3-Bromopropionic acid
CABFILs Carboxylic acid-based functional ionic liquids
CCU Carbon Capture Utilization
CCUS Carbon Capture Utilization and Storage
CCS Carbon Capture Storage
CILs Carboxyl-group-functionalized imidazolium-based ionic
liquids
CLPNs Cross-linked polymeric nanogels
CO2 Carbon dioxide
CPC Chloropropene carbonate
CPILM Cross-linked poly (ILs) membranes
[Cnmim]+ Alkyl-substituted imidazolium ions
[Cnpy]+ Alkyl-substituted pyridinium ions
DABCO 1,4-diazabicyclo[2.2.2]octane
DBPILs Bifunctional protic ionic liquids
DBU Diazabicyclo [5.4.0] undec-7-ene
[DBUH]C1 DBU hydrochloride
DFP Dicyandiamide–formaldehyde polymer
DFT Density functional theory
DILA DU based ionic liquids containing aluminium
DMAP 4-dimethylaminopyridine
[DMAPH]Br 4-(dimethylamino) pyridine hydrobromide
DMF Dimethylformamide
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DPP-MnCl Diphenylporphyrin]manganese(III) chloride
DVB Divinylbenzene
EC Ethylene carbonate
[emim][BF4] 1-Ethyl-3-methylimidazolium hexafluorophosphate
EtOH ethyl alcohol
FT-IR Fourier transform infrared spectrometer
GC-MS Gas chromatography- mass spectrometry
GP Glycidyl phenyl
HBD Hydrogen bond donor
H-bond Hydrogen bond
HEMIMB 1-(2-hydroxyethyl)-3-methylcarbazole bromide
ILs Ionic liquids
KI Potassium iodide
MOF Metal-organic framework
MPILs Metalloporphyrin ionic liquids
MTBD 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene
NMR Nuclear magnetic resonance instrument
[NRxH4-x]+ Alkyl-substituted quaternary ammonium ions
NTF2 Bis(trifluoromethanesulphonyl)imide
2-PAE 2-(phenylamino) ethanol
PBA Poly(butyl acrylate)
PC Propylene carbonate
P-CD P-cyclodextrin
PILs Protic ionic liquids
PO Propylene oxide
POP-TPP Metal porphyrin based porous organic polymer
[PRxH4-x]+ Alkyl-substituted quaternary phosphonium ions
PTAT Phenyltrimethylammonium tribromide
RTILs Room temperature ionic liquids
SC Styrene carbonate
SEM scanning electron microscope
SO Styrene oxide
TAPS Tetraarylphosphonium salts
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TBAB Tetrabutylammonium bromide
TBD 1,5,7-triazabicyclo[4.4.0]dec-5-ene
TGA Thermogravimetric analysis
TMG Tetramethyl guanidine
TOF Turnover frequency
TON Turnover number
TPP 5,10,15,20-tetra(4-pyridyl)-21H, 23H-porphine
ZIF-8 Zeolitic imidazole framework-8
ZnTPP Zinc 5,10,15,20-tetra(4-pyridyl)-21H, 23H-porphine
β-CD β-cyclodextrin
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Peer reviewed journal articles
➢ Xianglei Meng, Hong-Yan He, Yi Nie, Xiang-ping Zhang, Suo-jiang Zhang and Jianji Wang.
Temperature-Controlled Reaction–Separation for Conversion of CO2 to Carbonates with
Functional Ionic Liquids Catalyst. ACS Sustainable Chem. Eng., 2017, 5, 3081 (IF=6.970)
➢ Xianglei Meng, Zhaoyang Ju, Suojiang Zhang, Xiaodong Liang , Nicolas von Solms and
Xiangping Zhang,. Efficient Transformation of CO2 to Cyclic Carbonates by Bifunctional Protic
Ionic Liquids under Mild Conditions. Green Chem., (DOI: 10.1039/c9gc01165j) (IF=9.405)
➢ Xue Liu, Yi Nie, Xianglei Meng, Zhenlei Zhang, Xiangping Zhang and Suojiang Zhang DBN-
based ionic liquids with high capability for the dissolution of wool keratin. RSC Adv., 2017, 7,
1981. (IF=2.936)
➢ Zhibo Zhang, Jiahuan Tong, Xianglei Meng, Yingjun Cai, Feng Huo, Jianquan Luo, Suojiang
Zhang and Pinelo Manuel. Development of Novel Porphyrin-Based Ionic Liquids as biomimetic
light-harvesting for High Performance Enzymatic Conversion of Methanol from CO2. Green
Chem., (In peer review) (IF=9.405)
➢ Xianglei Meng, Ting Song, Xiaodong Liang, Xiangping Zhang, Suojiang Zhang and Nicolas von
Solms. Aluminum-containing Ionic Liquid for Cycloaddition of CO2 with Epoxides under Mild
Conditions. Catalysis Science & Technology (for submiting)
➢ Ting Song, Xianglei Meng, Xiangping Zhang, Suojiang Zhang, Peter Szaboa and Anders E.
Daugaard. Poly(Vim-co-BuA) membrane used for CO2 conversion into cyclic carbonates (Co-
first author for submiting)
Conference presentations
➢ Efficient Transformation of Atmospheric CO2 to Carbonates by DBU Based Ionic Liquids under
mild conditions. (Oral), CERE Annual Discussion Meeting, Denmark, June, 2018.
➢ Biological Porphyrin Ionic Liquids as Photocatalysts for Conversion of CO2 to Carbonates
(Poster), CERE Annual Discussion Meeting, Denmark, June, 2018.
➢ Efficient Transformation of CO2 to Carbonates by Functional Ionic Liquids under Mild Conditions.
(Poster), 9th Trondheim Conference on Carbon Capture, Transport and Storage. Norway, May,
2017
➢ Efficient Transformation of CO2 to Carbonates by Functional Ionic Liquids under Mild
Conditions. (Poster), CERE Annual Discussion Meeting, Denmark, June, 2017.
➢ The absorption and activation of CO2 by functional ionic liquids and it’s conversion at mild
conditions.
(Poster), CERE Annual Discussion Meeting, Denmark, June, 2016.
Center for Energy Resources Engineering Department of Chemical and Biochemical Engineering Technical University of Denmark
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