Gas Solid Chromatography on Ion Exchange

8/8/2019 Gas Solid Chromatography on Ion Exchange

1/16

J o u r n a l o f C h r o m a t o g r a p h y , 2 0 7 (1 9 8 1 ) 11S -1 3 0El se t i e r Scientif ic Publishing Company, Amsterdam - Printed in The NetherlandsCJ3ROM. 13,476GAS-SOLID CHROMATOGRAPHY ON CATION-EXCHANGE RESINS

DARC TOPOLOGICAL ANALYSIS OF THE BEHAVIOR OF ALKENES ONNICKEL IONS*

JACQUES R. CHtiT IEN and JACQUES-EMILE DUBOISIn & r u t d e T o p o r og i e e t d e Dy n a m i q u e d e s S y s t r ? m e s , A s s o c i P a u C .N .R . S . , Un i v e r s i t g Pa r i s VI I, 1 R u eGu y d e l a B r o s s e , 7 5 0 0 . 5Par i s (France )ROLAND F. HIRSCHDe p a r t m e n t o f Ch e m i s t r y , S e t o n H a l l Un i v e r s i t y , S o u t h Or a n g e , N J 0 7 0 7 9 (U. S . A .)andROBERT J. GAYDOSHA m e r i c a n Cy a n a m i d Co m p a n y , B o u n d B ro o k , N J 0 8 8 0 5 (U. S . A .)

SUMMARYRetention indices of 44 alkenes in gas-solid chromatography were determined

on the Ni2+ form of a cation-exchange resin and on the corresponding unsulfonatedcopolymer matrix. The Ni form was prepared from a sulfonated Porapak Q ethyl-vinylbenzene-divinylbenzene copolymer. DARC topological analysis (DTA) wasapplied to the KovBts retention indices determined at 175C. DTA helps to delineatethe evolution of specific z bond-Ni2+ ion interactions with progressive variations ofthe structural effects of the alkenes.

INTRODUCTIONGas-solid chromatography (GS C) on metal-containing surfaces is of con-

tinuing interest, particularly for the analysis of unsaturated hydrocarbons**. Suchanalyses are selective because of specific interactions due to the possibili ty of formationof charge-transfer compIexes3. Attention has also been drawn to the specific inter-actions between olefins and cations in gas-liquid chromatography when solutions ofdifferent salts or metal complexes are used. The high selectivity of stationary phasescontaining silver nitrate, particularly efficient for the separation of internal olefinicisomers, is well knowns. Different complexes of rhodium have a l s o been used6*.However, GS C has the advantage of enabling one to work at reIativeIy high tem-peratures, which significantly reduces the time of analysis. References to the use of

l Presented at the 6 t h I n t e rn a t i on a l Syn~po~ium Aivanc es a n d A p p k a f i o n of Ch ronu rrograp I~y i nI n d u s t r y , B r a r i s i a v a , S e p t e m b e r 1 6 -1 9 , I 9 8 0 .OOZl-9673/Sl/oooo-oooo / SOt .SO 0 1 9 8 1 Elsevier S cientific Publishing Company


2/16

116 I. R. CH&TIEN et a t_

metal-containing packings in GS C are numerous. Dif ferent cationic forms of zeolitesland ion-exchange resins8 have been used for the separation of various types of organiccompounds.The recent development of data processing methods applicable to chromato-graphy, including topological analysis of structural effectsgJO and factor analysis oftrends, has led to better quantification of these specific interactions12-1J. Suchinformation is useful both for improving the rapid analysis of hydrocarbons and fora physico-chemical understanding of catalysis. Indeed, similarities between chro-matographic and catalytic parameters, such as the type of support and its effects onadsorbates, are evident. The reactivity of alkenes in catalysis and their chromato-graphic adsorption on metal-ion-containing surfaces is governed by the strength ofthe specific interaction between the carbon-carbon double bond and the cation. Thisinteraction is dependent on the nature of the cation, its environment and the structuralenvironment of the carbon-carbon double bond. An example of this dependence isfound in the work of Jacobson and Pittmanls, who used polystyrene-divinylbenzeneresin anchored nickel complexes for selective oligomerizations and hydrogenations.McMunn et a/l6 studied the influence of the environment of the catalyst sites on theselectivity for various nickel and platinum forms as homogeneous and heterogeneouscatalysts_ Steric control of the alkyl group can also govern the selectivity in me-tathesis**. Furthermore, complementary information dealing with the possibil ities ofapproach of alkene molecuIes at the surface of a catalyst can be deduced from theirnon-specific adsorption in GS C on graphitized carbon black19. -

Within the framework of our study of GS C on cation-exchange resinss*20 wehave recently reported on trends in the selectivity of various hydrocarbons with thehelp of correspondence factor analysis (CFA). The role played by the cross-linkedethylvinylbenzene-divinylbenzene copolymer matrix and the relative chromato-graphic specificities of different cations (H +, K+, Tl*, Na, Ag, Ni+, Zn*+, Cdzf)have been delineated. We have now undertaken a more precise study of molecularstructural effects on specific interactions of a homogeneous series of alkenes withselected cations using the principle of DARC topological analysis (DTA) based onthe concepts of the DARC topological system (DARC is an abbreviation for descrip-tion, acquisition, retrieval and computer-aided design21-24). In this paper we presentthe first results, dealing with the specificity of the nickel form of the cation-exchangeresin.EXPERIMENTALA p p a r a tu s

All chromatographic work was carried out using a Varian Model 200 chroma-tograph with flame-ionization detectors (Varian Instruments, Palo Alto, CA, U.S.A.).The instrument was modified slightly to accomodate a calibrated thermometer inthe oven.

Glass columns (10 cm x 6 mm O.D.) were used. The packing material washeld in the column by silanized glass-wool plugs at the ends.Ultra-high-purity nitrogen (AGL Welding Supply, Clif ton, NJ, U.S.A.) was

used as the csirrier gas. All measurements were performed at 175C and with a carrierga s flow-rate of 40 ml/min.


3/16

GSC ON CATIO N-EXCHANGE RESI NS 117

P a c k i n g sThe preparation of lightly sulfonated resins was described previously. Thesulfonated resin (0.85 mequiv./g H+) was converted into the nickel form by passing ameasured volume of 0.1 M nickel nitrate solution through a glass column filled withdried resin. The converted resin was washed with water and then dried to 80C in avacuum oven for 4 h.The metal content of the resin was determined by atomic-absorption spectro-photometry on acid-digested samples. The particular resin used in this study con-tained 1.8 A of nickel. The unsulfonated form of the resin (UnS) consisted of PorapakQ (SO-100 mesh), obtained from Waters Assoc. (Milford, MA, U.S.A.).R e a g e n t s a n d ch e m i c a l sAll test compounds were of the highest purity commercially available andwere used as received (mainly from Aldrich, Milwaukee, WI, U.S.A., Tridom/Fluka,Hauppauge, NY, U.S.A., and Pfaltz and Bauer, Stamford, CT, U.S.A.). About 50 ~1of compound were placed in an air-fil led 30-ml butyl-rubber-stoppered bottle (PierceHypo-Vial, Pierce Chemical Co., Rockford, IL, U.S.A.). After mixing the contentsof the bottle, 10-15-4 samples of the vapor were withdrawn in a disposable hypo-dermic syringe fitted with a 25-gauge needle and inj ected into the instrument.R e t en t i o n d a t a

Retention times were determined by measurement of distances on the recorderchart tracings, after verifying that the chart speed control was accurate and precise.Kovats retention indices were calculated using the customary method with the normalhydrocarbons as reference compounds. The precision of the Kovits retention indicesreported was -& 3 units based on duplicate inj ections carried out in random sequence_D ata proces singFactor analysis of Kovats retention indices and other numerical techniqueschief ly stress stationary phase behavior. In order to understand fully the interactionbetween the solutes and the stationary phase with respect to the behavior of theindividual solute


4/16

graph

i; ; .traca l& -FO+.z&+m--m-.IDD2- -DDD;-

Fig. 1. Principle of superposition of the elementary graphs of some alkenes to give the characteristictrace of the population studied.

.

I /


5/16

TOOOCAYSOBHOOAKNOTHUUO

DSUOAOTHNC

FOMOTH

COEX

RN

Ema1a3accneKseeonca1CaKseeonnemsA

CeaoN

1

2

3

Nmocm

u

4

4

4

Nmopnme

1

1

2

CeaocceR

09

09

09

Saddaoa

48

12

9s

Aadaox

26

86

41

Ee1

00

00

00

Fe

1

1

3

-_

N

clpol

Gap

Umpaesu

Nomorh

BpC

E

C

D

EpCcD

WCD

(1

(2

(12(3

(4

(34(5

(53

-_

_

-

l 2 3 4 5 6 7 8 9 1 1 1 1Ehc

Poe

IBc

rosdBe

cs2Be

Ioe

2Mh1bc

2MhZe

IPe

fmZe

cs2Pe

23Dmhbc

33Dmh1bc

=

2

=

3

=

4

P

4

/ \=

4

=

3

-_

4

2 =

5

a

4

/J

5

\=

5

_C

5

J+

5

2

0

2

3

-2

3

3

5

4

4

1

4

4

6

,4

4

-4

5

4

-2

6

5

1

6

4

-2

5

5

0

5

5

2

5

5

7

6

5

-9

6

2 4 4 5 5 5 5 5 5 5 5 6 6

0

2

01

-17

-3

3

-1

7

-47

-4

4

38

-63

-1

4

37

09

-3

4

1

8

37

2

5

-4

1

-69

3

6

81

32

2

6

11

36

-3

5

-18

30

-1

5

-57

34

-7

5

-57

39

-2

6

07

SG

2

6

11

42

(C~op1


6/16

TA

cowd

_

-

-

-

NoConowl

Gap

U~pae~~

N*omorn

A

Bp

-

-_

EpCcD

EpCcm

CcD

(31

(0

(2

(1W1

(4

(34(5

(53

1 IS 1 1 1 1 2 2 2 2 2 2 2 22Ehbe

-z

5

2Mhpe

=

5

JMhpe

=C

5

4Mhpe

=

5

2MhZe

+

5

3Mha2pe

,=4

6

3Mhcs2pc

\

Gas Solid Chromatography on Ion Exchange

Documents

Transcript of Gas Solid Chromatography on Ion Exchange