Oxidation of alcohols with H2O2 catalyzed by bis-quaternary phosphonium peroxotungstates (or peroxomolybdates) under halide- and organic solvent-free condition

Several novel kinds of bis-quaternary phosphonium salts of peroxotungstate and peroxomolybdate, such as Ph3P(CH2)2PPh3[W(O2)4]·2H2O, Ph3P(CH2)2PPh3[WO(O2)2(C2O4)]·2H2O, Ph3P(CH2)3PPh3[W(O2)4]·2H2O, and Ph3P(CH2)2PPh3[MoO(O2)2(C2O4)]·2H2O, have been synthesized and characterized by elemental analysis, IR and Raman spectroscopy. Their catalytic properties in oxidation of cyclohexanol and benzyl alcohol to cyclohexanone, benzaldehyde or benzoic acid were investigated with aqueous 30% hydrogen peroxide under halide- and organic solvent-free conditions .