PURPOSE: The reaction of S-chloromethyloxirane with trimethylamine gives S-3-chlor-3-hydroxypropyltrimethylammonium chloride which is used as a syn thetic intermediate of carnitine in high yield.

CONSTITUTION: S-Chloromethyloxirane of formula I is allowed to react with trimethylamine hydrochloride to give 3-chlor-2-hydroxypropyltrimethyl-ammonium chloride. The compound of formula I is obtained by selective hydrolysis of the S-isomer of a glycerol derivative of formula III (R is 1W8C aliphatic hydrocarbon; R' is aromatic hydrocarbon) with lipase into an equimolar mixture of unreacting ester (R) of formula IV and an alcohol (S) of formula V, epoxidizing only the S-isomer by treatment with a base and separating the product by distillation.