Mechanisms of antioxidant action: products of the reaction between hydroperoxides and o-phenylene phosphites

Abstract

4-Methyl-2,6-di-t-butylphenyl o-phenylene phosphite (Ic) reacts with 1-methyl-1-phenylethyl hydroperoxide to give phenol, acetone, and α-methylstyrene as major products with acetophenone and 1-methyl-1-phenylethyl alcohol as minor products. At high ratios of hydroperoxide to phosphite, the former products which are formed by an acid catalysed reaction predominate, although a substantial proportion of the products formed by a radical induced decomposition are present under all conditions. At low hydroperoxide: phosphite ratios the product is almost entirely α-methylstyrene and can be accounted for on the basis of stoicheiometric reduction of 1-methyl-1-phenylethyl hydroperoxide to 1-methyl-1-phenylethyl alcohol. 4-Methyl-2,6-di-t-butylphenyl o-phenylene phosphate (IV) and its hydrolysis product the free acid (V) have been identified as products of the reaction. The former is formed both by reaction of the phosphite with hydroperoxide and with alkylperoxyl radicals.