Preparation Of Silver-copper Bimetallic Material And Their Application In Asymmetric Electroreduction Of Ethyl Benzoylformate

Chirality exists everywhere in nature,especially in the field of materials science and life science.In the field of life science,chiral drugs can be seen everywhere.However,the chiral substances in nature can no longer meet the needs of human beings.Therefore,a large number of researchers have devoted themselves to the study of chiral synthesis.Asymmetric reduction is one of the important methods for synthesizing chiral materials and it often use the chiral catalyst.Common heterogeneous chiral catalysts can be roughly divided into metal-inducer composite catalyst and metal complex catalysts.Regardless of the type of heterogeneous chiral catalyst,most of the central elements are precious metal elements,such as Pt,Rh,etc.,and the cost is very high.Moreover,most of these asymmetric reduction reactions use high-risk hydrogen,and the reaction conditions are mostly high pressure,which makes the reaction very risky.With more and more researches on chiral catalysts,non-precious metal chiral catalysts have been concerned gradually.In addition,the electrocatalytic asymmetric reduction reaction is also excellent in the field of asymmetric synthesis due to its advantages of green,safe and easy to operate.The above problems can be solved to a certain extent by combining cheap and easily available non-noble metal catalysts with green and safe asymmetric electroreduction in the reaction process.Nowadays,bimetallic nanomaterials have attracted much attention in the field of catalysis.In this kind of material,there is a certain synergistic effect between two metals,so that the material has better catalytic performance.In addition,such catalysts are heterogeneous catalysts,which are easy to be separated from the reaction system and can be reused.In this thesis,the silver-copper bimetallic material and the chiral-modified silver-copper bimetallic material were prepared by hydrothermal reduction method with simple operation and under mild conditions,and then these materials were used as working electrodes for asymmetric electroreduction reaction of ethyl benzoylformate.The electrolysis conditions were optimized to get relatively good results.The contents are as follows:?1?Preparation of silver-copper bimetallic material and their application in asymmetric electroreduction of ethyl benzoylformateSilver-copper bimetallic nanomaterials?Ag-Cu NPs?were prepared by hydrothermal reduction method using AgNO₃ and Cu?NO₃?₂·3H₂O as metal sources.And Ag-Cu NPs with different ratios of Ag and Cu were prepared by changing the molar ratio of Ag source to Cu source.The composition and morphology of the materials were characterized by XRD,TEM and SEM,and the electrochemical behaviors of the materials were detected by cyclic voltammetry.The Ag-Cu NPs were used as working electrodes for asymmetric electroreduction of ethyl benzoylformate,and the best result was obtained by optimizing the electrode materials,electrolysis potential,temperature,charge amount,and the types and dosages of chiral inducer.In addition,the reusability of the working electrode was investigated under the optimized condition.Finally,it was found that the yield and ee value of the target product ethyl mandelate were 42%and 54%respectively under the optimized conditions with Ag1-Cu1 NPs as the working electrode and cinchonidine?CD?as the chiral inducer,and the properties of the material did not change significantly after repeated use.?2?Preparation of CD-modified silver-copper bimetallic material and their application in asymmetric electroreduction of ethyl benzoylformateAg-Cu-CD NPs were prepared by modifying CD on Ag-Cu NPs,and a serial of Ag-Cu-CD materials with different ratios of Ag and Cu were prepared by changing the molar ratio of Ag and Cu.Similarly,the composition and structure of the materials were characterized by XRD,TEM and SEM.In addition,the CD in Ag-Cu-CD NPs were detected by TGA,FT-IR and UV.The Ag-Cu-CD NPs with different ratios of Ag and Cu were used as the working electrodes in the asymmetric electroreduction of ethyl benzoylformate.At the same time,the reusability of Ag-Cu-CD NPs was investigated under the optimization condition.Finally,it was found that the utilization rate of CD was increased by the modification of CD on Ag-Cu-CD NPs,and the expected goal of reusability was achieved.