Synthesis Of Primary Amines And Imines From Nitro Compounds By Heterogeneous Catalysis Of Non-noble Metals

Primary amines and imines are important industrial intermediates,which are widely used in medicine,pesticide,fine chemical industry and other fields.However,there are many problems in the industrial synthesis of primary amines and imines,such as harsh conditions,high energy consumption,high pollution and high cost.Therefore,it is very important to develop mild,green,and economic synthetic routes and methods.In this paper,from the perspective of using nitro compounds as substrates,high-activity,high-selectivity synthesis of primary amines and imines is achieved through the development of non-noble metal heterogeneous catalysts.（1）In this paper,the biomass carbon supported Ni catalyst（Ni/C-400）was prepared by one pot pyrolysis using the biomass material（cotton）as the carbon source.X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）,transmission electron microscopy（TEM）and other physical characterization techniques were used to characterize the catalyst.The characterization results showed that Ni nanoparticles were uniformly dispersed on the support.When the catalyst was applied to the reduction of nitro compounds,the Ni/C-400 catalyst was able to convert the nitro compounds into primary amines in a few hours under the condition of 25 ℃,5 bar H₂ and distilled water as solvent,showing very high catalytic activity.The Ni/C-400 catalyst is also highly selective for the synthesis of primary amines with its competitive functional groups（C=O,C=C,C-X,etc.）.In the development of substrate,Ni/C-400 catalyst showed good catalytic activity for aromatic and aliphatic nitro compounds,indicating that the application of catalyst is very wide.In addition,Ni/C-400 catalyst has good reusability without loss of activity.（2）From the perspective of further utilization of nitro compounds,this paper adopts one-pot reduction and coupling synthesis of imines by nitro compounds and aromatic alcohols.In this one-pot synthesis,alcohol is not only used as alkylating agent,but also as hydrogen source of nitro reduction,avoiding the use of additional hydrogen donors.Moreover,alcohol and nitro compounds have the advantages of low cost,good availability and stable chemical properties.In this paper,Co-N_X/C catalyst was prepared by hard template method and one pot pyrolysis method.X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）,transmission electron microscopy（TEM）and other physical characterization techniques were used to characterize the catalyst.The characterization results showed that the active site of the catalyst was Co-N_Xspecies.The Co-N_X/C catalyst was applied to the reductive coupling of nitro compounds and aromatic alcohols to synthesize imines.It was found that the catalyst has high activity and selectivity,and can synthesize imines under base-free and N₂ conditions.In addition,the catalyst showed good stability and reusability in the circulation experiment.