A Method for the Determination of the Structure of Saturated Branched-Chain Fatty Acids

Abstract

A method is described for the determination of the structure of branched-chain fatty acids. It is found that the carbon chain of methyl-branched acids can be readily degraded by potassium permanganate in acetone, to give a series of acids of decreasing carbon number. Where a branch occurs the acid series is interrupted and a methyl ketone, of the same carbon number as a missing acid, is produced. Gas chromatographic examination of the ketone(s) and esterified acids gives clear evidence for the location of the branch(es). The method is illustrated by application to tuberculostearic acid (10-methyl-octadecanoic acid) and C₂₇-phthianoic acid (2,4,6-trimethyltetracosanoic acid). It appears also able to decide the location of the ring in cyclopropane fatty acids.