Tandem synthesis of tertiary amines using graphene encapsulated Ni nanocatalyst via nitro compounds hydrogenation and primary amine methylation

Abstract

Development of the economic, environmentally friendly synthesis of amines from nitro compounds remains important and challenging. In this work, the graphene shell encapsulated none noble Ni-based catalysts were successfully designed and synthesized via an environmentally friendly method using H2O or EtOH as solvent. These fresh and recycling catalysts were characterized by X-ray diffraction and X-ray photoelectron spectroscopy. For the nitro compounds hydrogenation, Ni@C-600-H2O exhibits the best catalytic activity to achieve 100 mol/mol conversions of nitrobenzene and 99% selectivity of aniline under mild reaction conditions of 1.0 MPa H2 and 60 °C. Many halogen-substituted, olefin substituted nitro compounds and aliphatic nitro compounds were investigated and desired products were obtained in excellent selectivity. What is more, the catalyst had excellent stability and could be recycled 13 times without any significant loss in selectivity and activity. Furthermore, we also reported the methodology for tertiary amines synthesis using Ni-based catalyst via one-pot, cost-effective tandem combination reaction with nitrobenzene hydrogenation and amines N-methylation.