Preparation Of CD@Ag And Their Asymmetric Electrocatalytic Hydrogenation Of Ethyl Benzoylformate

Chirality is one of the common phenomena in nature and closely linked to life phenomena.Because of special pharmacological activities,chiral drugs have been concerned by more and more researchers.So the research and development of new chiral drugs is one of the main directions for medical field.In the process of the synthesis of chiral molecules,the choice of chiral catalysts is crucial.The suitable catalysts can not only improve the reaction efficiency greatly,but also reduce the experimental cost and the reaction difficulty effectively.Asymmetric catalysts can be divided into homogeneous catalysts and heterogeneous catalysts.Homogeneous catalysts are widely used in asymmetric catalytic studies with their superior selectivity and high catalytic activity.Common homogeneous catalysts include Ir,Rh and Ru complexes,which are not only expensive,but also have the problem of separation and recycling,so the heterogeneous catalysts come into being.Compared with the homogeneous catalysts,heterogeneous catalysts have certain advantages,such as easyseparation,recycling,and so on.However,small number of heterogeneous catalytic systems are proven to be effective.At the same time,the requirements of the reaction conditions of the heterogeneous catalytic system are usually very harsh.Most of the reactions require noble metals as catalysts and need high temperature,high pressure.In order to reduce the preparation cost of chiral catalysts and to recover easily,and to be carried out under mild conditions of the catalytic reaction,we have attempted to synthesize the organic@metal materials,CD@Ag film,CD@Ag NP and CD@Ag/TiO2 NP,and successfully applied materials to the reaction of asymmetric electrocatalytic hydrogenation of ethyl benzoyl formate(EB).The contents of this paper are as follows:(1)Preparation of CD@Ag film and the asymmetric electrocatalytic hydrogenation of EB.CD@Ag film was successfully synthesized by introducing CD as an inducer by electroless deposition principle.SEM,XRD,TEM,UV-Vis,TGA were used to characterize CD@Ag film.And it was applied directly as chiral catalyst to asymmetric electrocatalytic hydrogenation of EB.The electrode not only has good conductivity and catalytic activity of Ag,but also shows the inductive effect of CD on asymmetric catalytic hydrogenation of EB.The reaction was carried out under normal temperature and pressure,and ethanol was used as the hydrogen source to synthesize the optically active product-ethyl mandelate.The yield and ee value are 29%and 30%,respectively.(2)Synthesis CD@Ag NP and CD@Ag/TiO2 NP and their asymmetric electrocatalytic hydrogenation of EB.In the process of preparation of nano-silver,we prepared CD@Ag NP by adding CD.We used the same method to prepare CD@Ag/TiO2 NP.SEM,TEM,XRD,TGA and FT-IR were used to characteristic CD@Ag NP and CD@Ag/TiO2 NP.And they are applied directly as chiral catalyst to asymmetric electrocatalytic hydrogenation of EB.By selecting the preparation conditions and electrolytic conditions of the two groups of materials.The yield and ee values of asymmetric electrocatalytic hydrogenation of EB were 50%and 18%,respectively,when CD@Ag NP was used as the working electrode.When the CD@Ag/TiO2 NP was selected as the working electrode,the yield and ee values were 57%and 23%,respectively.By comparing two kinds of chiral nanomaterials,CD@Ag NP and CD@Ag/TiO2 NP,we found that the addition of TiO2 can not only play the role of refined metal nanoparticles,but also improve the content of organic matter in composite materials.Compared with the effect of two materials on electrocatalytic asymmetric hydrogenation of EB,we found that the addition of TiO2 has a certain improvement in the yield and ee value of the product.