Different Rates of Geometric Isomers of Linoleate Hydroperoxide in Acid-catalyzed Decomposition

Abstract

Methyl linoleate hydroperoxide was decomposed with 0.1 m HCl in acetone-water (9:1, v/v) at 30°C. The decrease in four isomers of the hydroperoxide was monitored by HPLC without any derivatization. In both isomers having 13- and 9-hydroperoxy groups, those having trans, trans dienes decomposed more rapidly than those having cis, trans dienes. In all the isomers, the rates of decomposition were first order with respect to concentrations of the hydroperoxides. The yields of 2-nonenal and 12-oxo-10-dodecenoate were also measured by GC-MS. 12-Oxo-10-dodecenoate was produced only from the 13-isomers and 2-nonenal from the 9-isomers. The rapid decomposition of the trans, trans isomers didn’t seem to be responsible for the formation of these aldehyde products.