Synthesis of bis-quaternary ammonium peroxotungstates (peroxomolybdates) and their catalytic activity in oxidation of alcohols by aqueous H2O2

Abstract

Three kinds of bis-quaternary ammonium salts of peroxotungstate and peroxomolybdate, such as PhCH2N-(CH2)6NCH2Ph[W(O2)4] · 2H2O, PhCH2N(CH2)6NCH2Ph[W-O(O2)2(C2O4)] and PhCH2N(CH2)6NCH2Ph[MoO(O2)2(C2O4)], have been synthesized and characterized. Their catalytic activity in the oxidation of cyclohexanol and benzyl alcohol was investigated with only aqueous 30% hydrogen peroxide. The results show that the bis-quaternary ammonium peroxotungstates are excellent catalysts in the oxidation of benzyl alcohol and cyclohexanol under moderate conditions. However, the catalytic ability of bis-quaternary ammonium peroxomolybadates is relatively poor. The yields of benzyl acid, benzaldehyde, and cyclohexanone reached up to 93.0%, 93.6%, and 91.7%, respectively.