Synthesis of Adipic Acid Catalyzed by Surfactant-type Peroxotungstate

A novel bifunctional amphiphilic quaternary ammonium isopolyperoxotungstate [C7H7C12H25(CH3)2N]2W2O3(O2)4 was synthesized for use as catalyst in clean synthesis of adipic acid.It was characterized by elementary analysis,gravimetry,chemical titration,TG-DSC and IR spectroscopy.Compared with the reported catalytic systems of tungstate,for oxidation of cyclohexene,cyclohexanol,cyclohexanone and 1,2-cyclohexanediol with 30% H2O2 to adipic acid,the catalytic activity of this compound was high under moderate reaction conditions without co-catalyst.Thus,the yield of adipic acid could reach 85.8% with n(cyclohexene)∶n(catalyst)∶n(H2O2)=100∶1.2∶538 reacting at 90 ℃ for 12 h.Under the same conditions,the yields from 1,2-cyclohexanediol,cyclohexanone and cyclohexanol were 88.5%,58.3% and 52.0% respectively.