Preparation Of Functional Materials Based On Chitosan And Polyethylene Glycol And Application In Aerobic Oxidation Reaction

The oxidation is one of the important reactions in the f ields of organic synthetic chemistry and fine chemical industry.Oxygen,as an ideal oxidant,has the advantages of low cost and easy availability,and environmental friendliness.A number of researchers have been devoted to developing catalytic oxidation system with molecular oxygen as terminal oxidant.On the other hand,due to the unique functional groups and physicochemical properties,polyethylene glycol and chitosan can be designed into a series of functionalized materials by means of cross-linking,grafting,and metal coordination,which shows broad application prospects in the field of chemical synthesis.However,there are relatively few green catalytic synthesis systems with high selectivity and high yield using chitosan and polyethylene glycol functionalized materials as catalysts or co-catalysts,with oxygen as the terminal oxidant.This article aims to design and synthesize a series of functionalized materials based on chitosan and polyethylene glycol and their applications in aerobic oxidation reaction.The main research contents and results are as follows:(1)This novel chitosan supported Rose Bengal photocatalyst(Chitosan-RB)successfully catalyzed the C-C and C-P bond formation of tertiary amines with various nucleophiles under visible light irradiation,which exhibited excellent catalytic activity.More impressively,the Chitosan-RB photocatalyst showed favorable recyclability and stability,which can be recycled nine times without significant loss of the catalytic activity.In addition,the reaction can proceed smoothly under the solar light irradiation.(2)A series of brominated polyethylene glycol functionalized ionic liquids were designed and synthesized.The effect of these ionic liquids on the selective oxidation of aromatic alcohols was investigated,and the effects of Cu Br dosage,ionic liquid amount and temperature on the reaction system were also discussed.It was found that the brominated polyethylene glycol functionalized ionic liquid modified with N,N-dimethylethanolamine shows the best promoting effect on the reaction.The catalytic system can efficiently catalyze the selective oxidation of aromatic alcohols without the addition of free radical initiators,volatile organic solvents or alkaline additives.Moreover,the catalytic system has excellent substrate applicability,and can be recycled five times without significant loss of the catalytic activity.(3)A series of amphiphilic chlorinated polyethylene glycol functionalized ionic liquids were developed to stabilize gold nanoparticles,and their catalytic performance on aer obic oxidation of α-hydroxyl ketone in water were investigated.As a result,it was found that the N-methylimidazole-modif ied chlorinated polyethylene glycol functionalized ionic liquid stabilized gold nanoparticles have small particle size,uniform distribution,and excellent catalytic activity.This catalytic system benefits from mild reaction conditions with high effic iency,simple operation procedures,a small amount of metal catalyst,good substrate applicability,especially no use of volatile organic solvents during the reaction process.