Study On Catalytic Oxidative Coupling Reaction By Anderson-type Polyoxometalates

Selective oxidation has always been one of the important and challenging topics in the field of chemistry.Traditional methods for selective oxidation of alcohol require the consumption of stoichiometric or larger amounts of oxidants,which have toxicity and high cost.Some reactions also produce stoichiometric metal salt waste or waste acid,which aggravates environmental pollution and other issues.As people attach importance to ecological environment,air,oxygen and hydrogen peroxide are considered to be very green oxidants,but this oxidation process usually requires catalysts.The catalyst is the core technology of green oxidation.The development of green,highly selective and highly active catalysts is an important research direction in the field of catalysis.Metal catalysts are one of the most popular choices,especially organometallic complex catalysts.In the past two decades,metal-organic catalysts have made significant progress in selective oxidation,however,in the process of catalytic oxidation,their instability,metal residue,difficulty in recycling and environmental unfriendly and other issues have always restricted their industrial applications.Therefore,we believe that the search for cheap and readily available metal catalysts will have significance both in theoretical research and industrial applications.In contrast,polyoxometalates are a very advantageous catalyst.They have unique redox properties,strong durability and environmental compatibility with oxidants.In recent years,polyoxometalates have played an important role in many catalytic reactions because of their rich characteristics.It is reported that there are few reports on the catalytic activity of Anderson polyacids with relatively simple structure,small molecular weight,and clear active sites.Based on the literature reports and results of our research group,this paper mainly investigates the catalytic oxidation coupling reaction by Anderson-type polyoxometalates.The work is mainly divided into the following three parts:(1)Oxidative coupling of amines to imine compounds by Cu-Anderson-type polyoxometalates as a metal catalyst supported by inorganic ligands catalysis.Simultaneously,the cross-coupling of alcohols and amines to asymmetric imine compound has been explored.(2)Fe-Anderson-type polyoxometalates catalyze the oxidation of organic halides to aldehydes or ketones,the oxidation of amines to imines,and the cross-coupling of alcohols with amines to imines.(3)The amide compound was prepared by oxidation of alcohol and amine using Cr-Anderson-type polyoxometalates catalyst.The reactions are carried out under mild reaction conditions.Molecular oxygen or hydrogen peroxide is used as an oxidant.The catalyst has good catalytic activity,excellent stability and durability,and the catalytic oxidation reaction can be easily expanded to gram,and the catalytic activity is hardly changed.In addition,we did a control experiment to make a simple speculation on the catalytic mechanism.