Catalytic Oxidation of Benzyl Alcohol by Dioxygen over Bidentate Schiff Base-Type Oxovanadium(IV) Complex Immobilized on Crosslinked Polystyrene Microspheres

The reaction between salicylaldehyde(SA) and aminomethyl(AM) group-modified crosslinked polystyrene(CPS) microspheres was allowed to be carried out,resulting in the SAAM-CPS microspheres,on which bidentate Schiff base-type oxovanadium(IV) complex was immobilized.Subsequently,the coordination reaction between SAAM-CPS microspheres and vanadyl sulfate was performed,obtaining Schiff base-type oxovanadium(IV) complex immobilized on the CPS-[VO(SAAM)2] microspheres,namely achieving the heterogeneous oxovanadium(IV) complex catalyst.The CPS-[VO(SAAM)2] microspheres were characterized by Fourier transform infrared,scanning electron microscope,and thermal gravimetric analysis.The complex catalyst was used in the oxidation of benzyl alcohol by dioxygen and the catalytic activity was examined.The experimental results show that,through the coordination reaction between SAAM-CPS microspheres and vanadyl sulfate,the immobilized Schiff base-type oxovanadium(IV) complex can be successfully prepared.In the oxidation of benzyl alcohol by dioxygen,the heterogeneous oxovanadium(IV) complex catalyst CPS-[VO(SAAM)2] has very high catalytic activity and excellent selectivity.Under the mild conditions such as at ordinary pressure of dioxygen and at a lower temperature of 90 oC,benzyl alcohol can be transformed to benzaldehyde as a single product with yield of 80%.The solvent porlarity affects the catalytic activity of the catalyst greatly.The stronger the solvent polarity,the higher the catalyst activity is and the higher the benzaldehyde yield is.The CPS-[VO(SAAM)2] catalyst has excellent reusability.