Production process for preparing parachloroaniline by catalytic hydrogenation of para-nitrochlorobenzene

Abstract

The invention discloses a production process for preparing chloroaniline by catalytic hydrogenation of para-nitrochlorobenzene. The meta-chloroaniline is prepared by catalytic hydrogenation of para-nitrochlorobenzene as raw material in methanol as solvent in the presence of Raney-Ni catalyst and dicyandiamide as a dechlorination inhibotor at 55 DEG C under 1 MPa. According to the process, the selectivity of parachloroaniline is more than 98.5%, and the dechlorination rate is less than 0.5%.

Description

technical field [0001] The invention relates to a production process of p-chloroaniline, in particular to a production process for preparing p-chloroaniline by using a hydrogenation process. Background technique [0002] p-Chloroaniline is an important fine chemical intermediate, widely used in the production of pesticides, dyes, pharmaceuticals and other fine chemicals. Traditional nitro reduction methods mainly include iron powder reduction method, alkali sulfide reduction method, catalytic hydrogenation reduction method, and electrochemical reduction method. The iron powder reduction method produces a large amount of iron sludge, which seriously pollutes the environment; the alkali sulfide reduction method has disadvantages such as complex reduction routes, low product yield, and large waste liquid; the electrochemical reduction method consumes too much energy; the catalytic hydrogenation method has a reaction route Short, low energy consumption, environmental friendline...

AI Technical Summary

Problems solved by technology

The iron powder reduction method produces a large amount of iron sludge, which seriously pollutes the environment; the alkali sulfide reduction method has disadvantages such as complex reduction routes, low product yield, and large waste liquid; the electrochemical reduction method consumes too much energy; the catalytic hydrogenation method has a reaction route Short, low energy consumption, environmental friendly and other advantages

However, in the process of preparing p-chloroaniline by catalytic hydrogenation of p-nitrochlorobenzene, the side reaction of hydrogenolysis and dechlorination to generate aniline easily occurs due to the C-Cl bond on the benzene ring in the presence of a metal catalyst, thereby reducing the yield of the main product. Rate

At the same time, the hydrogen chloride generated by dechlorination will also cause corrosion to equipment