Catalytic oxidation of toluene by ozone in the system "acetic anhydride–strong acid"

Abstract

The process of catalytic oxidation of toluene by ozone in the solution of a mixture "acetic anhydride–a strong acid" has been studied in the presence of compounds of transition metals. It is shown that the main oxidation products in the system Mn(Ac)2–(СН3СО)2О–Н2SO4 at 200C are benzylacetate and benzylidene diacetate with the yields of 39% and 29%, respectively. In the system Со(Ac)2–(СН3СО)2О–НА, the reaction is accompanied mainly by the formation of benzylidene diacetate (68.0%) and the yield of benzylacetate does not exceed 4.0%. The kinetic parameters of the main stages of the catalytic cycle were investigated. It was found that strong acids play a decisive role in increasing the activity of oxidized forms of the metal. Under the conditions of activation by strong acids, the reaction of methylbenzene with Me3+ occurs with a high degree of substrate conversion. It was found that the reduction of Me3+ in the reaction with the solvent becomes noticeable, along with the oxidation of toluene, with increasing the concentration of strong acids. It was stated that the selective oxidation of toluene under catalysis is initiated by the reaction with an oxidized form of the metal formed by the interaction of ozone with the catalyst.