Terpenoid: CXVI. Evaluation of polyesters as stationary phases in gas-liquid chromatography of terpenoids

Abstract

Polyesters from ω-hydroxy acids have been prepared by self polymerisation and evaluated as substrates for gas-liquid chromatography. Two model compounds, (1)ω-hydoxy-stearic acid and (2) aleuritic acid, which are easily available from indigenous sources, were employed for polyesterification. In the case of aleuritic acid, where cross-linking is freely possible, the usual process of ester formation was not found useful. It gave a rubber-like mass, insoluble in common organic solvents. Therefore a novel method of polyester formation on the supporting material in situ is described for both the hydroxy acids. Such polymers, when applied to the analyses of the monoterpenic oxygenated compounds, showed acid catalysed isomerisation of the sample vapours. A successful attempt has been made to retard this process of isomerisation. These polyesters showed very high solubilities for the nonpolar sesquiterpenic hydrocarbons and can be used for the separation of monoterpenic oxygenated compounds and sesquiterpenic hydrocarbons. Simultaneously, the effect of "unsaturation in the polyester" has also been studied by synthesising two polyesters, one from adipic acid and 1,4-butanediol and the other from adipic acid and 1,4-butenediol. The effect of "unsaturation" is found to be opposite to that which is observed in the case of long chain dicarboxylic acid diethylene glycol polyesters. The unsaturated polyester shows better solubilising powers for oxygenated compounds than for hydrocarbons.