Study On The Catalysts For The Amination Of Alcohols And Ketones

Amines are a class of important nitrogenous organic compounds,and widely applied in pharmaceuticals,agricultural chemicals,dyes and polymer material auxiliary agents.Among the numberous synthetic methods for amines,the amination of alcohol or ketone is the most applicable one.Thus,the catalysts for efficient syntheses of several important organic amines were investigated systematically in this paper,based on the catalytic amination of alcohols,the reductive amination and the amination-dehydrogenative aromatization of ketones.（1）The selective catalytic amination of diethylene glycol with dimethylamine to bis（2-dimethylaminoethyl）ether（BDMAEE）was studied.The screened catalyst Cu₂₀Cr₇Co₅/Al₂O₃ achieved the highest diethylene glycol conversion and BDMAEE selectivity of 99.6%and 55.2%,respectively,under the optimized reaction conditions.The prepared catalysts were studied by various characterization methods.It was found that the doped Cr and Co not only promoted the dispersion of Cu nanoparticles,but also regulated the acidity of the catalysts,resulting in the excellent selectivity towards BDMAEE.Additionally,the catalyst also showed good stability.（2）On the basis of the above work,so as to expand the application of Cu-based catalysts in the synthesis of amine compounds,the reductive amination of levulinic acid was studied by the model reaction of levulinic acid with n-butylamine to N-alkyl-5-methyl-2-pyrrolidone.Through the improvement and optimization of Cu-based catalysts,it was found that the boron-doped catalyst,Cu₁₀/Al B₃O exhibited excellent catalytic performance,the conversion of levulinic acid and the selectiveity towards the corresponding pyrrolidone reached to 99.4%and 94.4%,respectively.Additionally,the catalyst also showed good generality to various primary amines.After detailed characterization of the prepared catalysts,it was found that the doped boron not only enhanced the dispersion of Cu and provided more active sites for the reductive amination,but also changed the electron density of surface Cu species and acidity of catalyst,leading to the promotion of the hydrogenation activity and stability.（3）Taking into account the problems of harsh reaction conditions and low yield of the traditional synthetic method of diphenylamine,and inspired by the reaction mechanism of reductive amination.The amination-dehydrogenative aromatization of cyclohexanone and aniline to diphenylamine was studied.Through the screening and optimization of the catalysts,Pd₁/Al₃BaO was chosen as the catalyst for the above-mentioned reaction,84.7%yield of diphenylamine was achieved.The catalyst also exhibited good stability.It was found that the doped Ba suppressed the agglomeration of Pd nanoparticles,and also diminished the acidity of catalyst,which was beneficial to the desorption of the product and facilitated the formation of diphenylamine.