The preparation of fatty acid chlorides

Abstract

Fatty acid chlorides of lauric, myristic, palmitic, stearic, oleic, elaidic, and linoleic acids were prepared using phosphorus tri- and pentachlorides, oxalyl chloride, and thionyl chloride as chlorinating agents. On the basis of yields, ease of handling, and cost of reagent, phosphorus tri- and pentachlorides are superior to other chlorinating agents for the preparation of the higher fatty acid chlorides for use as intermediates in the preparation of pure saturated fatty acid glycerides of known structure. The unsaturated fatty acid chlorides are, however, best prepared from oxalyl chloride. The use of phosgene, which has been patented for the preparation of acid chlorides, failed to effect efficient conversion of the higher fatty acids to the corresponding chlorides. The analysis of the fatty acid chlorides by conversion to anilides provides a simple and easy means for ascertaining the extent of conversion of fatty acids to chlorides. By means of this method it is possible to follow readily the course of the reaction in order to determine when complete conversion of fatty acid to fatty acid chloride has been effected.