Ozonization products of unsaturated fatty acid methyl esters

Abstract

Low temperature ozonization of the methyl esters of all- cis nonconjugated fatty acids, containing 1 to 4 double bonds in pentane, gave high yields of normal ozonides of the parent ester as the major product of the reaction. Ozonization of all- cis methyl eicosapentaenoate and docosahexaenoate under the same conditions gave a mixture of normal ozonides containing a large proportion of cross ozonides. Thin-layer chromatography (TLC) of the normal ozonides of the methyl esters of unsaturated fatty acids differing in the number and positions of ozonide groups and in chain length was demonstrated. Fractionation of the parent normal ozonides of methyl linoleate, linolelaidate, linolenate and arachidonate by low temperature crystallization indicated that the normal ozonides of these esters consisted of mixtures of geometric isomers. The ozonization of the methyl esters of all- trans nonconjugated fatty acids gave low yields of normal ozonides of the parent ester by comparison to the corresponding all- cis isomers, and the yield of these ozonides decreased with increasing unsaturation. Infrared spectral analysis showed that the major products of the reaction with these esters contained both hydroxyl and/or peroxy and normal ozonide groups.