Zn(0)-Catalysed Mild And Selective Hydrogenation Of Nitroarenes/Preparation Of High Purity Chiral Amine By Racemization

This thesis mainly consists of two parts:?1?New zinc catalyst for selective hydrogenation reduction of aromatic nitro compounds;?2?Research on obtaining high-purity chiral amines by combining biological and chemical methods to racemizeAromatic primary amines are important cornerstones for the production of pesticides,pigments,dyes,drugs and polymers,and are often used as important intermediates in the production of many fine chemicals and drugs.Although the formation of aromatic primary amines has been receiving much attention,most reactions will encounter many problems:most catalytic systems rely on the use of pressurized molecular hydrogen or stoichiometric sodium iron sulfite-mediated hydrogenation precious metal catalysts or non-metallic catalysts.Metal catalysts,which use organic solvents as reaction solvents,require high-temperature reaction conditions and have high requirements for the reaction equipment,and the yield of the target product is not very high,resulting in increased preparation costs or a lot of waste of metal salt/slurry flow,even May cause serious environmental problems.The preparation of chiral amine compounds has been widely concerned by scientific researchers.The traditional methods of racemization to obtain high-purity chiral amines mostly rely on chemical methods or kinetic resolution of biological methods that require expensive coenzymes.Not only the yield of chiral amines is low,but also the reaction cost is increased,so development is urgently needed.A low-cost and high-yield method for obtaining chiral amines.The first part of this paper proposes a relatively green and environmentally friendly,non-precious metal zinc preparation catalyst.The catalyst is characterized by EA,ICP-OES,TEM,XRD,XPS and HH COSY to achieve the Determine the purpose.Compared with other methods,this method not only has simple operation,mild reaction conditions,but also has high yield and high selectivity.During substrate expansion,an interesting phenomenon was discovered.For nitroaromatic hydrocarbons containing ketone carbonyl groups,only nitro groups were selectively reduced without reducing ketone carbonyl groups.This phenomenon also exists for nitro compounds containing aromatic olefins.Selective reduction of nitro without reducing the double bond in the fatty chain.Finally,a recycling experiment was carried out on the catalyst,and it was found that it still has more than 90%catalytic activity and excellent selectivity after four cycles.In order to better explain the role of the catalyst in the reaction,the corresponding reaction mechanism is proposed.Finally,the purified target product was characterized by ¹H NMR and ¹³C NMR.In the second part of this paper,we propose to use?-aminotransferase as a biocatalyst to work with non-precious metal catalysts to de-racemate amino donors to obtain high-purity chiral amines.This article does not use the expensive coenzyme NAD?P?H,racemic?-phenethylamine as a reaction model.The transaminase uses one of the configuration amino donors at the same time to resolve the racemic amino donor to obtain Chiral amines with high optical purity,the by-product acetophenone reacts with hydroxylamine hydrochloride to form acetophenone oxime,which is reduced to the substrate model?-phenethyl amine under the action of non-noble metal organic catalyst,Then continue to participate in the reaction,and finally achieve the purpose of obtaining a chiral amine with high optical purity.