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Gas chromatography of homogolous esters
of Chmnar~graph~,
loumal Ekvier
Scicnttic
Publishing
250 ( 1952) 9699 Company. Amsterdam
-
Printed
in The Nsthcrh~d~
Note
Gas chromatography XVllP.
of homologous
Polychlorinated
propionate
esters and butyrate
esters
Sowit
E&r
J. K. HXKEN Departmenf
! .hsrralia
0,’ Po!rmrr
Science.
Lnirersity
of .Vrw
H’aie3,
P.O.
I.
Kerrrin,orott.
S.S.Ii’. 2033
I
A recent paper’ has considered the retention bzhaviour of the methyl and chloromethyl esters of isomer+ monochloro esters of Ca-C18 n-carboxyIic acids? and of the corresponding monochloro esters of the isomeric C5 aliphatic acids’. The effect on retention of the position of the chlorine substituent and of branching in thz acid chain shown in these reports was compared ivith the results from other studies on aliphatic esters containing a second and variable structural parameters. The prsent work extends the earlier study using recently available data”*’ on the mono- and dichloro esters of n-butyric acid and on ali the chlorinated esters of in all of the propionic acid ‘m9such that the effect on retention of chlorine substituents positions in the chain is apparent.
A Yarinn Model 3-Z-00 gti chromntograph with flame ionisation detector was used for the analyses. Glass capillary columns coated with 3 7; Carbowaa 20&I iv:re u-4 with temperature programming from 5O’C at 6’C/min. The retention data were recorded as uncorrected retention times. RESULTS ASD DISCUSSlOS
The retention data for the methyl esters of mono- and dichlorobutyric acids are shown in Table I while the retention behaviour relative to the position of substitution is shown in Fig. 1. The monocbloro esters follow the trend previously observed for longer chain esters. where the xtention increased with the distance of the chlorine atom from the carbonyl group, the w- or terminally substituted compound having the highest retention due to minimisation of acceptor-donor efEets. 01’ the diehloro esters the 2,Shomologue has, predictably, the lowest retention time while the 3,3- and 4,4_homoIogues show progressively higher retention times, the l
Pa-t .YVIIr G. Crank
0011-9673152,
cxJaLMm,
and J. K. Haken.
502.75
S
1. Chromaro,or.,
1953. Elxrisr
Scicntitic
145 (1952)
Publishing
36_U9. Company
97
NOTES TABLE I RETENTION
TIMES OF MONO- AND DICHLOROBUTYRATE
Compound
Uelenrion
ESTERS
rime
(see)
hkthyl Methyl Methyl Methyl Methyl Methyl Methyl hlethyl Methyl Methyl
butyrate 2cblorobutyrzte Schlorobutyrate L1dichlorobutyratc J-chlorobutyrate 3.3dichIorobutyratc er_hro-2.3dichlorobutyrate rlzreo-1.34ichlorobutyrate 444chlorobutyrzte ZJ-dichIorobutyrzte
141 _ 22’33 248 287 3-N 340 374 484 513 561
Methyl
XJ-dichIorobutymte
595
compounds folIowing the pattern of the 2-, 3- and 4chJoro esters. The retention time of the 2,3-dichloro isomer is ‘hitier than that of the 3,3-isomer. that of the 2,4-isomer is similarly higher and the 3.4-dichloro ester shows the highest retention time. The polar effect of two chlorine substituents is maximised when the two atoms are not attached to the same carbon atom, which is simply due to the bulkiness of the substituents.
Cl
0
c-c-c-c-
Cl
Cl
c
c-c-c-hCl Cl
i-c -c-cl CI
0 II Cl I C-C-C-CCl I
CI I
Cl I
c-c-c-cF;.g I. Structure zmd retention behztiour
of mono- and dichlorobutyrates.
0
I1 0 II
NOTES
9s
TABLE
I1
RETESTIOS
TIMES OF METHYL
CHLOROPROPIOSATES
.\lPl/-:.I.!
Reicnriorz rime fs.%,
clrloropropi~nares
195 11s 169 315
2-Chlmopropionate -I ‘-Di:hloropropionatt -3-Chloropropiotute 3.~-Dichloropropion~te 2.‘3-Dichloropropianctc 3.3.5Trichloropropionars X3-Trichloropropionatc ‘;.3_Trichloropropianlrc ~.j.;.;-Te~chloropropi~n~te
407
3-s 4% 533 594 MS 759
“7.j_T~tmchlilropropionarc: P~n:a~hloropropion~re
_.____
Cl
c
c,_;_c_;_
Fig. 2. Structure and retention kha\iour
of methyl chloropropioaates.
NOTES
99
The effect of further substitution may be observed from the data of the eleven methyl chloropropionates (Table II) while the retention bchaviour relative to the position of the substituents is shown in Fig. __ 3 The increase in retention in the monoand dichloropropionates followed the same pattern as for the corresponding butyrate esters. As expected, the trichloropropionates have increased retention times and the 3,3,3-trichloro ester. due to attachment of three substituent goups, exhibits a lower retention than the 3.2,3-trichloro ester which. in turn. has a tower retention than the 2.3.3~isomer
\\-ithterminal di-substitution.
The same pattern is observed for the two tetra-substituted isomers, where terminal di-substitution produces greater retention than terminal tri-substitution. The pentachloropropionate. with an additional chlorine substituent. shows the greatest retention of the series. The two ester series generally follow the same retention pattern with substitution, and it is possible, by observin g the following simF!e rules. to predict the elution behaviour of longer chain polychlorinated esters. (I) The retention of an ester with single chlorine substitution increases as the distance from the carbonyl increases and retention is maximised with substitution in the terminal (w) position. (2) W,C) di-substitution produces lower retention than CL).CJ - 2 and w,w - 1 di-substitution. (3) With trichloro esters retention is maximised with odi-substitution. The retention data. if available as retention indices. would allow the relative contributions of each substituent to be shown as retention increments as have been used with many series of saturated and unsaturated aliphatic esters. REFERENCES
J. K. H&en, J. Chrunmrogr., 243 ( 1932) 9. I. 0.0. Korhonen. J. Chronrmogr.. 209 (1951) 96. 1.0.0. Korhonen. J. Chromarogr.. 211 (1981) 267. 1. 0.0. Korhonen. J. Chromrogr.. 219 (1981) 306. 1. 0. 0. Korhoncn. 1. Chrotmtogr.. in press. 6 51. Pilksnen. 1. 0. 0. Korhonsn and J. N. J. Konola. Te~ra/redron. 37 ( 1951) 397. 7 I. 0.0. Korhonen. Acta Chenr. Srund. Ser. B. 35 (1951) 175. S 1. 0. 0. Korhonen. 1. Chromafogr.. 213 ( 19s I ) 63. 9 1. 0. 0. Korhontn and J. N. J. Konola Am C/UWI. Scarrd Ser. B. 35 (1951) 139. I 7 3 1 5
loumal Ekvier
Scicnttic
Publishing
250 ( 1952) 9699 Company. Amsterdam
-
Printed
in The Nsthcrh~d~
Note
Gas chromatography XVllP.
of homologous
Polychlorinated
propionate
esters and butyrate
esters
Sowit
E&r
J. K. HXKEN Departmenf
! .hsrralia
0,’ Po!rmrr
Science.
Lnirersity
of .Vrw
H’aie3,
P.O.
I.
Kerrrin,orott.
S.S.Ii’. 2033
I
A recent paper’ has considered the retention bzhaviour of the methyl and chloromethyl esters of isomer+ monochloro esters of Ca-C18 n-carboxyIic acids? and of the corresponding monochloro esters of the isomeric C5 aliphatic acids’. The effect on retention of the position of the chlorine substituent and of branching in thz acid chain shown in these reports was compared ivith the results from other studies on aliphatic esters containing a second and variable structural parameters. The prsent work extends the earlier study using recently available data”*’ on the mono- and dichloro esters of n-butyric acid and on ali the chlorinated esters of in all of the propionic acid ‘m9such that the effect on retention of chlorine substituents positions in the chain is apparent.
A Yarinn Model 3-Z-00 gti chromntograph with flame ionisation detector was used for the analyses. Glass capillary columns coated with 3 7; Carbowaa 20&I iv:re u-4 with temperature programming from 5O’C at 6’C/min. The retention data were recorded as uncorrected retention times. RESULTS ASD DISCUSSlOS
The retention data for the methyl esters of mono- and dichlorobutyric acids are shown in Table I while the retention behaviour relative to the position of substitution is shown in Fig. 1. The monocbloro esters follow the trend previously observed for longer chain esters. where the xtention increased with the distance of the chlorine atom from the carbonyl group, the w- or terminally substituted compound having the highest retention due to minimisation of acceptor-donor efEets. 01’ the diehloro esters the 2,Shomologue has, predictably, the lowest retention time while the 3,3- and 4,4_homoIogues show progressively higher retention times, the l
Pa-t .YVIIr G. Crank
0011-9673152,
cxJaLMm,
and J. K. Haken.
502.75
S
1. Chromaro,or.,
1953. Elxrisr
Scicntitic
145 (1952)
Publishing
36_U9. Company
97
NOTES TABLE I RETENTION
TIMES OF MONO- AND DICHLOROBUTYRATE
Compound
Uelenrion
ESTERS
rime
(see)
hkthyl Methyl Methyl Methyl Methyl Methyl Methyl hlethyl Methyl Methyl
butyrate 2cblorobutyrzte Schlorobutyrate L1dichlorobutyratc J-chlorobutyrate 3.3dichIorobutyratc er_hro-2.3dichlorobutyrate rlzreo-1.34ichlorobutyrate 444chlorobutyrzte ZJ-dichIorobutyrzte
141 _ 22’33 248 287 3-N 340 374 484 513 561
Methyl
XJ-dichIorobutymte
595
compounds folIowing the pattern of the 2-, 3- and 4chJoro esters. The retention time of the 2,3-dichloro isomer is ‘hitier than that of the 3,3-isomer. that of the 2,4-isomer is similarly higher and the 3.4-dichloro ester shows the highest retention time. The polar effect of two chlorine substituents is maximised when the two atoms are not attached to the same carbon atom, which is simply due to the bulkiness of the substituents.
Cl
0
c-c-c-c-
Cl
Cl
c
c-c-c-hCl Cl
i-c -c-cl CI
0 II Cl I C-C-C-CCl I
CI I
Cl I
c-c-c-cF;.g I. Structure zmd retention behztiour
of mono- and dichlorobutyrates.
0
I1 0 II
NOTES
9s
TABLE
I1
RETESTIOS
TIMES OF METHYL
CHLOROPROPIOSATES
.\lPl/-:.I.!
Reicnriorz rime fs.%,
clrloropropi~nares
195 11s 169 315
2-Chlmopropionate -I ‘-Di:hloropropionatt -3-Chloropropiotute 3.~-Dichloropropion~te 2.‘3-Dichloropropianctc 3.3.5Trichloropropionars X3-Trichloropropionatc ‘;.3_Trichloropropianlrc ~.j.;.;-Te~chloropropi~n~te
407
3-s 4% 533 594 MS 759
“7.j_T~tmchlilropropionarc: P~n:a~hloropropion~re
_.____
Cl
c
c,_;_c_;_
Fig. 2. Structure and retention kha\iour
of methyl chloropropioaates.
NOTES
99
The effect of further substitution may be observed from the data of the eleven methyl chloropropionates (Table II) while the retention bchaviour relative to the position of the substituents is shown in Fig. __ 3 The increase in retention in the monoand dichloropropionates followed the same pattern as for the corresponding butyrate esters. As expected, the trichloropropionates have increased retention times and the 3,3,3-trichloro ester. due to attachment of three substituent goups, exhibits a lower retention than the 3.2,3-trichloro ester which. in turn. has a tower retention than the 2.3.3~isomer
\\-ithterminal di-substitution.
The same pattern is observed for the two tetra-substituted isomers, where terminal di-substitution produces greater retention than terminal tri-substitution. The pentachloropropionate. with an additional chlorine substituent. shows the greatest retention of the series. The two ester series generally follow the same retention pattern with substitution, and it is possible, by observin g the following simF!e rules. to predict the elution behaviour of longer chain polychlorinated esters. (I) The retention of an ester with single chlorine substitution increases as the distance from the carbonyl increases and retention is maximised with substitution in the terminal (w) position. (2) W,C) di-substitution produces lower retention than CL).CJ - 2 and w,w - 1 di-substitution. (3) With trichloro esters retention is maximised with odi-substitution. The retention data. if available as retention indices. would allow the relative contributions of each substituent to be shown as retention increments as have been used with many series of saturated and unsaturated aliphatic esters. REFERENCES
J. K. H&en, J. Chrunmrogr., 243 ( 1932) 9. I. 0.0. Korhonen. J. Chronrmogr.. 209 (1951) 96. 1.0.0. Korhonen. J. Chromarogr.. 211 (1981) 267. 1. 0.0. Korhonen. J. Chromrogr.. 219 (1981) 306. 1. 0. 0. Korhoncn. 1. Chrotmtogr.. in press. 6 51. Pilksnen. 1. 0. 0. Korhonsn and J. N. J. Konola. Te~ra/redron. 37 ( 1951) 397. 7 I. 0.0. Korhonen. Acta Chenr. Srund. Ser. B. 35 (1951) 175. S 1. 0. 0. Korhonen. 1. Chromafogr.. 213 ( 19s I ) 63. 9 1. 0. 0. Korhontn and J. N. J. Konola Am C/UWI. Scarrd Ser. B. 35 (1951) 139. I 7 3 1 5