One-pot Synthesis Of N-methylaniline And N, N-dimethylaniline From Nitrobenzene And Methanol

As versatile intermediates,N-methylaniline and N,N-dimethylaniline are wildly used in synthesis of paints,dyes,medicines,pesticides.They are mainly produced from aniline and methylating reagents,and aniline is usually obtained from catalytic hydrogenation of nitrobenzene.Additionally,methanol is considered to be the most economical and eco-friendly methylating reagent of aniline.In the previously work,we have realized a novel liquid system of catalytic hydrogenation of unsaturated compounds,and one-pot synthesis of N-ethylaniline from nitrobenzene and ethanol.In the present work,an one-pot synthetic method for synthesis of N-methylaniline and N,N-dimethylaniline is proposed.Catalyzed by pretreated(at 443 K in the methanol for 8 hours) Raney-Ni, N-methylaniline and N,N-dimethylaniline were produced through one-pot synthesis from nitrobenzene and methanol.In such a process,methanol acts as "hydrogen source","alkylating reagent",and "solvent",simultaneously,individual hydrogenation of nitrobenzene with hydrogen in methanol ect.as solvent for aniline is avoided.The effects of reaction temperature,reaction pressure and reaction interval for N-methylaniline,and the effects of catalyst,start materials,reaction temperature, reaction pressure and reaction interval for N,N-dimethylaniline were investigated. Catalyzed by Raney-Ni,a yield of N-methylaniline up to 70%was obtained from 60 ml methanol and 10 ml nitrobenzene at 413 K and 1.4 MPa;up to 98%overall of N,N-dimethylaniline was obtained from 60 ml methanol and 2 ml nitrobenzene at 443 K and 3.0 MPa. The mechanism of proposed methodology was explored by investigating separate reactions of the production of N,N-dimethylaniline as example.Additionally,main by-products were also described.