Gas liquid chromatography of the hydroxy‐, acetoxy‐and oxo‐stearic acid methyl esters

Abstract

Abstract Carbon numbers have been determined for all the 17 isomeric methyl hydroxy‐ and acetoxystearates and for 15 of the 16 isomeric methyl oxostearates using silicone SE‐30, silicone QF‐1, and ethylene glycol succinate (EGS) as liquid phases. The carbon numbers of the isomers increase with increasing distance of the point of substitution from the carboxyl end of the fatty acid chain (the increases for the 4‐ and 5‐hydroxy esters are unexpectedly large). The change in carbon number from one isomer to the next is greatest when the substituents are attached near either end of the chain. The best separation of isomers with the substituent near the carboxyl end is obtained for oxo esters using the QF‐1 column, and that of isomers substituted near the methyl end is obtained for acetoxy esters using the EGS column. Isomers with substituents at carbons 9<13 are not distinguishable on any of the columns used, but the other isomers are partly or completely separated. The quantitative aspects of the separations have not been investigated.