Identification of novel octadecadienoic fatty acids in the seaweedCladophora rupestris through oxidative ozonolysis of the alcohols prepared from the acids

The BF 3 −MeOH reagent for ozonolysis of ethylenic unsaturation does not oxidize alcohols. It is therefore feasible to determine the position of ethylenic unsaturation in long chain fatty alcohols of synthetic or natural origin by recovering the methyl ester products intact and silylating the alcohol function of half‐ester, half‐alcohol, products prior to gas liquid chromatographic analysis. The C 3 fragment from methylene‐interrupted alkyl chains is not recovered, but, by first reducing carboxyl ester groups to alcohols, the terminal difunctional products can be identified in nonmethylene‐interrupted dienoic fatty acids. The seaweed Cladophora rupestris is shown to contain Δ5,Δ11‐,Δ8,Δ11‐, and Δ11, Δ14‐ as well as Δ9,Δ12‐octadecadienoic acid.