Mechanism of the reactions of oxygen with fatty materials. Advances from 1941 through 1946

Summary A review of advances from 1941 through 1946 in the mechanism of the oxygen oxidation of fatty materials is given. Subjects discussed are the oxidation of monounsaturated compounds, nonconjugated and conjugated polyunsaturated compounds, and saturated compounds. The hydroperoxide theory of oxidation at active methylene groups is discussed in detail. There is good justification for postulating that autoxidative attack in olefins is initiated universally by addition of oxygen at the double bonds in only a few of the molecules, and not by the formation of hydroperoxides. Subsequently, in the case of monoolefins and nonconjugated polyolefins, the attack by oxygen is continued by substitution on the α‐methylene group to form hydroperoxides by means of chain reactions . Mechanisms for such an oxidative scheme, involving the formation of intermediate free radicals, are given. In the case of conjugated compounds, peroxides are formed by addition of oxygen at the double bonds, and α‐methylene group peroxidation does not occur. Although saturated compounds are relatively inert, they also form hydroperoxides, which are converted mainly to ketones and alcohols with the ketones predominating. The formation of polymers, which often account for the major proportion of the oxidation products of unsaturated compounds, also is discussed. The possibility of formation of carbon‐to‐carbon‐linked as well as oxygen‐linked polymers in the various classes of olefins is considered.