AUTOXIDATION OF METHYL LINOLEATE AND METHYL LINOLENATE AND REACTIONS OF THE HYDROPEROXIDES FORMED IN NORMAL-HEPTANE SOLUTION

Methyl linoleate and methyl linolenate upon autoxidation in n-heptane solution in daylight as well as in the dark are converted into a mixture of hydroperoxides with a cis.trans conjugated diene structure, in which the hydroperoxy group is attached to one of the allylic methylene groups. The initiation reaction is a combination of a thermal and photochemical reaction between the methyl esters and oxygen. The hydroperoxides decompose into the corresponding hydroxy and keto compounds. The stoichiometric and kinetic parameters of these reactions in the absence and presence of cobalt(II) or cobalt(III) naphthenate were determined. During the final stage of the autoxidation of the methyl esters fragmentation of the C-C chain and formation of oxo bridges between the methyl ester molecules were observed. Diene polymerization appeared to be inhibited by oxygen. © 1979, American Chemical Society. All rights reserved.