Immobilizing Aminophenol Type Bidentate Schiff Base Oxovanadium(Ⅳ) Complex on Surfaces of CPS Microspheres and Its Catalytic Oxidation Property

Esterification reaction between glyoxylic acid (GA) and chloromethylated crosslinked polystyrene (CMCPS) microspheres was made to be carried out,and the aldehyde group (AG) was introduced onto the surfaces of crosslinked polystyrene (CPS) microspheres,resulting in the modified microspheres CPS-AG.Subsequently,the Schiff base reaction of the AG on CPS-AG microspheres was conducted using m-aminophenol as reagent,obtaining the functional microspheres CPS-AGAP,on which aminophenol type bidentate Schiff base ligands were bonded.Finally,the chelating coordination reaction between CPS-AGAP microspheres and vanadyl sulfate was performed,and microspheres CPS-VO(AGAP)₂,on which aminophenol type bidentate Schiff base oxovanadium(Ⅳ) complex was immobilized,were successfully prepared.The effects of the main factors on the esterification reaction between GA and CMCPS microspheres were studied and the reaction conditions were optimized.The microspheres CPS-VO(AGAP)₂ were fully characterized by Fourier Transform Infrared spectroscopy (FT-IR),Ultra-Violet spectrum (UV) and Scanning Electron Microscope (SEM).The microspheres CPS-VO(AGAP)₂ were used in the oxidations of cyclohexanol and ethylbenzene with molecular oxygen as oxidant,respectively,and their catalytic activity was examined.Results showed that the polarity of the solvents was advantageous to the esterification reaction between GA and CMCPS microspheres,and the suitable solvent was N,N-dimethylacetamide with strong polarity.The appropriate reaction temperature was 90℃.Under the optimum reaction conditions,the conversion of the chloromethyl group of CMCPS microspheres could reach 82%.In the aerobic oxidations of cyclohexanol and ethylbenzene,CPS-VO(AGAP)₂ microspheres exhibited fine catalytic activity.