Isolation of pure linolenate as its mercuric acetate adduct

After addition of mercuric acetate to the unsaturated methyl esters obtained from the methanolysis of linseed oil, linolenate of 99% minimum purity was isolated by means of a liquid‐liquid continuous extraction technique and subsequent decomposition of the mercurial adduet. The methyl linolenate‐mercuric acetate addition compound was extracted with 10% methanol in water from an ether solution of the reaction mixture. Infrared analysis of the regenerated methyl linolenate showed the complete absence of trans ‐linkages. The yield, at least 60% of the linolenic acid present in linseed oil, was considerably higher than that obtained by bromination‐debromination procedures. The solubility in aqueous solutions of fatty acid derivatives having 3 or more acetoxymer‐euri‐groups/molecule provides an approach to the fractionation of highly unsaturated oils. For example, a fraction having an iodine value of 395 was isolated readily from the methyl esters of pilchard oil by this technique.