S1

The efficient C-C bond formation between two

levulinic acid molecules to produce C10

compounds with the cooperation effect of

Lewis and Brønsted acids

Zheng Li, †,‡

Jiaojiao Zhang, †,‡

Michael Martin Nielsen,§ Hongliang Wang,

ǁ Chunyan

Chen, † Junli Xu,

‡ Yingxiong Wang,

† Tiansheng Deng,*

,† Xianglin Hou*

,†

†The Biorefinery Research and Engineering Center, Institute of Coal Chemistry,

Chinese Academy of Sciences, 27 South Taoyuan Road, Taiyuan 030001, P. R. China

‡University of Chinese Academy of Sciences, Beijing, 100039, P. R. China

§Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-210

0 Copenhagen, Denmark

ǁCenter of Biomass Engineering/College of Agronomy and Biotechnology, China

Agricultural University, Beijing, 100193, P. R. China

*Corresponding author

Email: dts117@sxicc.ac.cn (Tiansheng Deng)

Email: houxianglin@sxicc.ac.cn (Xianglin Hou)

total number of pages: 12

total number of figures: 11

S2

Materials:

Levulinic acid (99 wt%) was purchased from Langfang Haoke Technology Co.,

Ltd. Sulfuric acid, hydrochloric acid, Trichloroacetic acid and zinc bromide were

purchased from Sinopharm Chemical Reagent Co., Ltd. Zinc chloride, zinc acetate,

stannic chloride, cupric chloride and zinc sulfate were purchased from Tianjin

Kemiou Chemical Reagent Co., Ltd.

Experiment:

In the dimerization reaction 50 mmol LA was added into a 25 mL flask in an oil

bath and the reaction system was stirred during the whole process. The 13

C NMR,

DEPT135 and 1H-

13C HSQC spectra were recorded in D2O

on Bruker AV-III 400 at

frequencies of 400.13 and 100.61 MHz, respectively. LC-MS was performed with

Shimadzu LCMS-2020 with a VP-ODS column (2.0mm×250mm). The mobile phase

was acetonitrile and water (20:80 v/v) at 0.2mL/min. ATR-IR was performed using

Nicolet iS10 FT-IR spectrometer in the range from 400 to 4000cm-1

.

TMDFA quantitative measurement

The residual LA in reaction mixture was determined by using a Shimadzu

high-pressure liquid chromatograph (LC-10AT) equipped with a UV-VIS detector

(SPD-10A). A 4.6 mm id×250 mm Ultra AQ C18 column was used. The mobile

phase was constituted by acetonitrile and 0.7 wt% phosphoric acid aqueous solution

(20:80 v/v) at 0.5 mL/min. The column temperature was maintained at 40 °C. The

conversion of LA was calculated on the basis of external standard curves with

authentic standards. The yield of TMDFA was calculated based on the results of 1H

NMR spectra with the following equation (S1):

yield = 2 �� ������������������

�� ������������× �1 − conversionofLA* × 100% (S1)

S3

Purification of products

First, ethyl acetate and water were used to extract the reaction mixture and

remove ZnCl2 and TCA. Then, the products dissolved in EtOAc was separated by

flash column chromatography. The stationary phase was silica gel (48~75µm) and the

eluent constituted of 55% ethyl acetate, 40% petroleum ether and 5%formic acid.

TLC: The eluent: ethyl acetate/petroleum ether (2/1), 5% formic acid. Rf (LA):

0.72; Rf (products): 0.59.

S4

Fig. S1 1H NMR spectrum of purified products.

Fig. S2 13

C NMR spectrum of purified products.

S5

Fig. S3 DEPT-135° NMR spectrum of purified products.

Fig. S4 1H-

13C HSQC spectrum of purified products.

S6

Fig. S5 1H-

1H COSY spectrum of purified products.

1H NMR (400 MHz, CDCl3) δ 2.87 [s, C(5)-H, 2H], 2.71[t, C(3)-H, 2H], 2.60 [t,

C(2)-H, 2H], 2.58 [C(8)-H, 2H], 2.24 [m, C(7)-Ha, 1H], 2.08 [m, C(7)-Hb, 1H], 1.41

[s, C(10)-H, 3H].

13C NMR (101 MHz, CDCl3) δ 205.61, 178.13, 177.01, 84.36, 51.99, 38.17,

32.49, 28.86, 27.64, 26.64.

1H NMR (400 MHz, CDCl3) δ 3.41 [t, C(3)-H, 1H], 3.09[m, C(2)-Ha, 1H], 2.59

S7

[C(8)-H, 2H], 2.58 [C(2)-Hb, 1H], 2.24 [m, C(5)-H, 3H], 2.22 [m, C(7)-H, 2H], 1.20

[s, C(10)-H, 3H].

13C NMR (101 MHz, CDCl3) 203.81,178.03, 174.30, 85.14, 55.49, 35.85, 31.10,

31.03, 28.56, 21.15

S8

Fig. S6 LC-MS spectrum of LA.

Fig. S7 LC-MS spectrum of TMDFA.

To further verify this assumption, LC-MS spectra and other NMR technologies

including Distortionless Enhancement by Polarization Transfer 135° (DEPT135) and

1H-

13C Heteronuclear Single Quantum Coherence (

1H-

13C HSQC) were employed. As

shown in the LC-MS spectra (Fig. S6, S7), pure LA displayed a more intensive

quasi-dimer ion peak than the quasi-molecular ion peak (Fig. S6). Thus, the peak of

m/z 213 originated from molecular weight of 214, consistent with that of TMDFA and

MOTOA (Fig. S7).

S9

4000 3500 3000 2500 2000 1500 1000 500

2360

1382

1403

1299

1207

1182

17101735

3033

Transmittance(%)

Wavenumber (cm-1)

3417

941

1076

Fig. S8 FTIR of isolated product

The FTIR spectrum of isolated product are shown in Fig. S8. The stretching

vibration area of hydroxyl in dissociative carboxylic acid is at 3417cm-1

and it in the

dimer of carboxylic acid is at 3300-2800 cm-1

. The wavenumber of C=O in lactone

and carboxyl are 1735 and 1710 cm-1

, respectively. The peaks at 1403 and 941 cm-1

could be ascribed to the flexural vibration of C-O-H. And the absorption peak of CH3

is at 1382cm-1

. The peak of 1207cm-1

could be ascribed to the stretching vibration

CO-C.

S10

0 100 200 300 400 500 600 700 800

0

10

20

30

40

50

Conversion&yield (%)

Time (min)

Conv.

yield

ZnCl2+TCA 110 °C

0 10 20 30 40 50 60 70 80

0

10

20

30

40

50

60 ZnCl2+TCA 150 °C

Conversion&yield (%)

Time (min)

Conv.

Yield

0 100 200 300 400 500

0

10

20

30

40

50

60

ZnCl2+TCA 120 °C

Conversion&Yield (%)

Time (min)

Conv.

Yield

0 100 200 300 400 500

0

10

20

30

40

50

ZnCl2 120 °C

Conversion&Yield (%)

Time (min)

Conv.

Yield

0 50 100 150 200 250 300

0

10

20

30

40

50

60 ZnCl2+TCA 130 °C

Conversion&Yield (%)

Time (min)

Conv.

Yield

0 50 100 150 200 250 300

0

10

20

30

40

50

Conversion&Yield (%)

Time (min)

ZnCl2 130 °C

Conv.

Yield

0 20 40 60 80 100 120

0

10

20

30

40

50

60

ZnCl2+TCA 140 °C

Conversion&Yield (%)

Time (min)

Conv.

Yield

0 20 40 60 80 100

0

10

20

30

40

Conversion&Yield

Time (min)

ZnCl2 140 °C

Conv.

Yield

Fig. S9 The conversion of LA and the yield of TMDFA as a function of time in

different catalytic conditions.

S11

0 50 100 150 200 250 300

0.00

0.01

0.02

0.03

0.04

0.05ZnCl2+TCA 120 °C

k=1.7174∗10-4

R2=0.995

Time (min) 0 100 200 300 400 500

0.00

0.01

0.02

0.03

0.04

0.05

ZnCl2 120 °C

k=9.4293∗10-5

R2=0.994

Time (min)

0 50 100 150 200 250

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

ZnCl2+TCA 130 °C

k=3.1988∗10-4

R2=0.996

Time (min) 0 50 100 150 200 250 300

0.00

0.01

0.02

0.03

0.04

0.05

ZnCl2 130 °C

k=1.7325∗10-4

R2=0.9798

Time (min)

0 20 40 60 80 100

0.00

0.01

0.02

0.03

0.04

0.05

0.06ZnCl2+TCA 140 °C

k=6.7714∗10-4

R2=0.988

Time (min) 0 20 40 60 80 100

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035 ZnCl2 140 °C

k=3.6962∗10-4

R2=0.999

Time (min) Fig. S10 The reaction rate fitting lines in different conditions.

The C-C bond formation reaction was proposed as a second-order reaction, and

its rate-equation integral was as follow:

kt =/

�0× �

1

/21* (S2)

where k represents the reaction rate, t represents the reaction time, c0 and x represent

initial concentration of LA and the conversion of LA, respectively.

S12

0.00242 0.00244 0.00246 0.00248 0.00250 0.00252 0.00254 0.00256

-8.8

-8.6

-8.4

-8.2

-8.0

-7.8

-7.6

-7.4

-7.2

ZnCl2+TCA

intercept=19.62

slope=-11132.41

lnk

1/T 0.00242 0.00244 0.00246 0.00248 0.00250 0.00252 0.00254 0.00256

-9.4

-9.2

-9.0

-8.8

-8.6

-8.4

-8.2

-8.0

-7.8

ZnCl2

intercept=18.89

slope=-11082.00

lnk

1/T

Fig. S11 The fitting lines of kinetics parameters in different conditions.

From the fitting line of the relationship between lnk and 1/T, the activation

energies and pre-exponential factors were calculated.