Preparation Of The Immobilizing Aminophenol Type Schiff Base Oxovanadium???complex And Investigatiion Of Its Catalytic Oxidation Property

Under the action of the catalyst,the transition from alcohol to carbonyl compounds is achieved by using molecular oxygen or air as oxidant.Immobilized Schiff base transition metal complex catalyst has excellent catalytic activity,selectivity and good reusability in the process of catalytic oxidation of alcohols with molecular oxygen substances,and can effectively oxidize the alcohol to the corresponding aldehyde or ketone.This study through molecular design,the functional microspheres CPS-AGAP,which were linked with aminophenol-type Schiff base ligands,were prepared by two-step macromolecule reaction and based on the cross-linking polystyrene microspheres as a carrier.The chelating coordination reaction between CPS-AGAP microspheres and vanadyl sulfate,cobalt acetate,manganese acetate was performed,and microspheres CPS-[VO?AGAP?₂],CPS-[Co?AGAP?₂],CPS-[Mn?AGAP?₂],CPS-[Cu?AGAP?₂],onwhich aminophenol type Schiff base metal complex was immobilized,were successfully prepared.The microspheres were used in the oxidations of cyclohexanol and 1-phenyl ethanol with molecular oxygen as oxidant,respectively,and the catalytic activity,selectivity and catalytic oxidation mechanism of these heterogeneous catalysts were investigated.The results of this study have important scientific significance and potential application value in the field of catalytic oxidation of green alcohol.Esterification reaction between glyoxylic acid and chloromethylated crosslinkedpolystyrene?CMCPS?microspheres was carried out,and the aldehyde group?GA?was introduced onto the surfaces of crosslinked polystyrene?CPS?microspheres,resulting in the modified microspheres CPS-AG.Subsequently,the Schiff base reaction of the GA on CPSAG microspheres was conducted with m-aminophenol as reagent,obtaining the functional microspheres CPS-AGAP,on which aminophenol type Schiff base ligands were bonded.The influence factors of the main factors on the preparation of functional microspheres were optimized and the reaction conditions were optimized.Finally,CPS-AGAP microspheres were chelated with vanadium sulfate,cobalt acetate,copper nitrate and manganese acetate,respectively.Four kinds of solid catalysis CPS-[VO?AGAP?₂],CPS-[Co?AGAP?₂],CPS-[Mn?AGAP?₂] and CPS-[Cu?AGAP?₂] which immobilized aminophenol type Schiff base transition metal complexes were successfully prepared.The microspheres were fully characterized by infrared spectroscopy?FT-IR?,electronic absorption spectrum?UV?and scanning electron microscope?SEM?.Results showed that the polarity of the solvents was advantageous to the esterification reaction between glyoxylic acid 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 can reach 82%.The resulting solid catalyst microspheres CPS-[VO?AGAP?₂],CPS-[Co?AGAP?₂],CPS-[Mn?AGAP?₂] and CPS-[Cu?AGAP?₂] were prepared and the maximum amount of the surface metal species were0.78mmol/g,0.75mmol/g,0.71mmol/g and 0.69mmol/g,respectively.Four kinds of aminophenol type Schiff base transition metal complex microspheres were used to catalyze the molecular oxygenoxidation process of cyclohexanol and 1-phenyl.The effect of main factors on oxidation was investigated and the mechanism of catalytic oxidation was the explored.The experimental results show that the four kinds of catalyst microspheresshow a certain catalytic activity and excellent selectivity in the catalytic reaction of cyclohexanol and 1-phenyl,and can catalyze the process of molecular oxygen oxidation of cyclohexanol and 1-phenyl under mild conditions.Catalytic oxidation has a high selectivity.Cyclohexane and acetophenone are the only product of the reaction.Compared with the catalytic effect of catalyst microspheres,the catalytic effect was CPS-[VO?AGAP?₂]>CPS-[Co?AGAP?₂] > CPS-[Mn?AGAP?₂] > CPS-[Cu?AGAP?₂],and the catalytic effect of CPS-[VO?AGAP?₂] was the best.0.78 mmol of catalyst microspheres CPS-[VO?AGAP?₂] was added and reacted at 90°C for 30 h,The catalyst microspheres CPS-[VO?AGAP?₂] can efficiently convert cyclohexanol to cyclohexanone at a conversion rate of 64%.0.546 mmol of catalyst microspheres CPS-[VO?AGAP?₂] was added and reacted at 80°C for 28 h,The catalyst microspheres CPS-[VO?AGAP?₂] can efficiently convert 1-phenyl to acetophenone at a conversion rate of 78%.Oxygen vanadium catalyst CPS-[VO?AGAP?₂] has a high catalytic activity,mainly due to the high valence of vanadium atoms on the molecular oxygen has high affinity,and has a high coordination number.When the CPS-[VO?AGAP?₂] was used for 7times,the conversion rate of cyclohexanol was almost stable at about 64% and the conversion rate of 1-phenyl was almost stable at about 73%,which indicated that the immobilized catalyst CPS-[VO?AGAP?₂] had good cycle performance.