Ilpo O.O. Korhonen

Retention increments of isomeric chlorobenzenes

The chlorobenzene isomers are used extensively as intermediates in a wide range of chemical products. More recently their determination in environmental situations has become of considerable importance and chromatographic procedures have been widely reported for their determination in both trace and major amounts. There are over 220 publications in which gas chromatography (GC) has been applied to the analysis of chlorobenzene. However, over 60 o/o of these works refer to the separation of only one isomer. Relatively few publications’-8 consider all the isomers, although the use of both capillary3’ and packedcolumns with polar and non-polar stationary phases has been reported. Temperature programming and isothermal operation have been used, with retention times, relative retention times and retention ratios being variously reported. The effect on retention of increasing chlorine substitution has not been reported and this paper shows the incremental effect in terms of retention indices on a non-polar (SE-30) and a polar (Carbowax 20M) capillary column. The elution order of the isomers is compared with that reported previously.

Gas chromatography of homologous esters. XX: Capillary column studies of alkyl acetates, chloroacetates, dichloroacetates and trichloroacetates

Abstract Isothermal capillary gas chromatography of C1-C8 n-alkyl acetates, chloroacetates, dichloroacetates and trichloroacetates has been studied using a low-polarity (SE-30) and a polar (OV-351) stationary phase at increasing temperatures from 100 to 160°C. The work extends recent studies of Komarek and co-workers and shows the effect of retention index increments on the methylene chain and of the various chlorine substituents in the individual homologous series.

Gas—liquid chromatographic analyses : IX. Glass capillary gas chromatography of aliphatic C1 C8 n-alkyl monochloro esters of acetic, chloroacetic, Dichloroacetic and trichloroacetic acids☆

Abstract The gas chromatography (GC) of n-alkyl acetates (CH3COOR), chloroacetates (CH2ClCOOR), dichloroacetates (CHCl2COOR) and trichloroacetates (CCl3COOR), where the alcohol chain length (R) varied between 1 and 8, and certain of their monochlorinated derivatives, 176 compounds altogether, has been studied on SE-30 and OV-351 glass capillary columns under the same operating conditions. The isomeric monochlorinated esters are eluted in direct order from the 1- chloro to the ω-chloro isomer, the separation of the isomers being complete on OV- 351. On SE-30, however, the peaks of the 6- and 7-chlorooctyl esters are partly overlapped. The separation of the mixtures of odd- and even-carbon-number esters was better on a non-polar column. The GC analysis of the combined mixtures of all isomers resulted in several overlapping peaks, particularly with the chloroacetates. The isomeric chloro esters are eluted on SE-30 in the order mono-, di- and trichloro isomers, whereas on OV-351 the di- and trichloro esters are eluted in the reverse order while the 1-chloroalkyl C2 C8 trichloroacetates are eluted before the corresponding monochloro isomers. A different elution order of the compounds is observed on a polar column, 1 -chloro and ω-chloro isomers giving rise to the greates difference in elution order. The gas chromatograms of the mixtures and the relative retention times of the compounds are given.

Gas chromatography of homologous esters : XXI. Capillary column studies of the chlorinated phenyl acetates

Abstract The gas chromatographic retention behaviour of the series of chlorinated phenyl acetates has been studied on SE-30 and OV-351 quartz capillary columns at 160, 180 and 200°C. Retention index measurements for each position of substitution together with the effect of increasing temperature on retention are discussed. The relative effect of polar and steric effects are considered and it is evident that major retention variations due to either effect do not occur.

Gas—liquid chromatographic analyses : XXXV. Capillary column studies of C1C12n-alkyl esters of benzoic and monochlorobenzoic acids☆

Abstract The gas chromatographic retention behaviour of C1C12n-alkyl esters of benzoic acid and monochlorobenzoic acids was studied on low-polarity (SE-30) and polar (OV-351) capillary columns under various isothermal and temperature-programmed operating conditiions. The relative retention data, the retention indices and the retention index increments for the methylene unit and the chlorine substituents were determined and the retention order of the invidiual components in the mixture is discussed. The results are compared with those reported previously for aromatic esters.

Gas—liquid chromatographic analyses : XXVI. Separation of unsaturated alcohols and their acetyl and haloacetyl derivatives on capillary columns coated with se-30 and ov-351

Abstract The gas chromatographic retention behaviour of seven unsaturated alcohols and the corresponding esters of acetic, mono-, di- and trichloroacetic and mono-, di- and tribromoacetic acids on a low-polarity (SE-30) and a highly polar (OV-351) capillary column with temperature programming is reported. The relative retention data and the retention indices, with the retention index increments due to the methylene unit and the various halogen substituents, were determined. The retention order of the individual components in the mixtures is discussed, together with the influence of unsaturation and boiling point. The results are compared with those of earlier studies.

Gas—liquid chromatographic analyses : XXIV. Capillary column studies of the chlorinated veratroles (1,2-dimethoxybenzenes)☆

Abstract The gas choromatographic retention behaviour of veratrole and all nine chlorinated veratroles was studied on SE-30 and OV-351 capillary columns. Temperature programming from 100°C at 6°C min−1 and isothermal operation at 140, 160, 180 and 200°C were used. The complete separation of a mixture was obtained on SE-30, the isomers being eluted in order of their degree of chlorination. On OV-351, however, the 3,4,5-trichloro and tetrachloro isomers overlap with temperature programming, being separated at 140, 160 and 200°C. Retention indices and increments of retention indices for each position of substitution are examined and the effect of increasing temperature on retention is discussed.

Gas—liquid chromatographic analyses : XXVIII. Capillary column studies of chlorinated anisoles☆

Abstract All nineteen ring-substituted chloroanisoles were separated on non-polr (SE-30) and polar (OV-351) capillary columns under various temperature-programmed and isothermal conditions. The relative retention data for the isomers were examined, together with the retention indices and the increments of retention indices for each position of chlorine substitution. The retention order of the compounds is discussed and the results are compared with those reported earlier for chloroanisoles and chlorinated phenyl acetates.

Gas chromatography of homologous esters. XXIX: Propanoyl and monochlorpropanoyl esters of lower saturated branched-chain and unsaturated alcohols

Abstract The gas chromatographic retention behaviour of the propanoyl and monochloropropanoyl esters of saturated C3C5 branched-chain and unsaturated C3C6 alcohols on SE-30 and OV-351 capillary columns at several temperatures is reported. Retention index increments at 80 and 120°C show the effect of branching in the alkyl chain and also the effect of unsaturation and of its position in the chain with chlorination at the two possible positions in the acyl chain. The various incremental effects are discussed and compared with the behaviour of the corresponding n-alkyl esters.

Gas—liquid chromatographic analyses : XXXVII. Capillary column studies of benzoyl and monochlorobenzoyl esters of lower saturated branched-chain alcohols

Abstract The gas chromatographic retention behaviour of methylethyl, 1-methylpropyl, 2-methylpropyl, 1,2-dimethylpropyl, 1-methylbutyl and 3-methylbutyl esters of benzoic and o-, m- and p-chlorobenzoic acids on low-polarity (SE-30) and polar (OV-351) capillary columns under several temperature-programmed and isothermal conditions is reported. The retention data and the Kovats retention indices for all 24 components are given and the separation of a complex mixture is discussed. The retention index increments have been used to examine the effects of chain branching and chlorine substitution. The results are compared with those for n-alkyl benzoates and monochlorobenzoates.