The main differences in reactivity of mono- and diunsaturated fatty acid esters during aerobic oxidation

Abstract

During the aerobic oxidation of esters of both mono- and diunsaturated fatty acids and their mixtures, epoxide compounds are first forming, as well as the peroxide compounds with different structures and reactivities depending on the number of double bonds in the original molecule. The mild aerobic oxidation conditions in the column-type apparatus led to a number of features of the process. It was shown that both types of esters are consumed in independent ways, despite the fact that the whole process is radical. Therefore, this means the absence of processes of transfer of oxidation chains, as well as the chains of radical reactions themselves. Thus, we can conclude that the process under study is radical without chain transfer from one type of ester to another. Peroxides forming from monounsaturated fatty acid esters are able to participate in catalytic epoxidation by hydroperoxides, which proceeds with high selectivity. From diunsaturated fatty acid esters, at least two types of peroxides with different reactivities are formed. One of them can enter into catalytic epoxidation reaction, the other forms secondary oxidation products, which are mainly represented by the products of the Baeyer–Villiger reaction. In this contribution upon using different mono- and diunsaturated fatty acid esters, the mechanism of products formation has been investigated and discussed.