The Oxidation of α-Methylstyrene in the Presence of Benzaldehyde

The oxidation of α-methylstyrene in the presence of benzaldehyde was studied at 40°C, with and without added metal salt catalysts, from the viewpoint of the products obtained. The products were α-methylstyrene oxide, acetophenone, formaldehyde, α-methylstyrene polyperoxide, perbenzoic acid, and benzoic acid; few side reactions between these products were observed under the reaction conditions employed here. Emphasis was laid on the effect of metal salt catalysts and of the initial composition of the oxidants on the cleavage products from α-methylstyrene. Manganese and copper salts were found to have little effect, while cobalt salt showed a characteristic effect on the formation of the cleavage products. In the presence of cobalt salt, the formation of acetophenone was accelerated. The increase in the formation of α-methylstyrene oxide in this system compared with the oxidation of α-methylstyrene alone may well be attributed to the polar reaction of α-methylstyrene with perbenzoic acid formed from benzaldehyde. The consumption of perbenzoic acid in various systems was also examined. The increase in the initial concentration of benzaldehyde increased the yield of α-methylstyrene oxide and decreased that of acetophenone.