Chlorinated aromatic amines

#The invention relates to a process for the preparation of chlorinated aromatic amines by selective hydrogenation of chloronitro-aromatic compounds.

#As is known, the hydrogenation of chlorinated aromatic nitro compounds is accompanied by a more or less extensive dechlorination, depending on the hydrogenation catalyst used (J. prakt. Chem. 317, Number 2, page 247 (1975). The consequences are a reduction in the yield of the desired halogenated amines and extensive corrosion in the apparatuses as a result of the hydrogen chloride formed. It is an object of the present invention to minimise dechlorination.

#Various processes are already known, with the aid of which attempts are made to keep the elimination of chlorine as low as possible. According to these processes, either the hydrogenation catalyst is specially modified or a dehalogenation inhibitor is added to the customary catalyst during the reaction.

#The aromatic nitrochloro compound, the solvent, the catalyst and the sulphur compound, which is optionally dissolved in water or in an organic solvent, are initially introduced into an autoclave.

#(In order to ensure that the medium is basic during the entire reaction, a base can optionally be added.)

#The autoclave is flushed, first with nitrogen and then with hydrogen. The reaction mixture is then heated to the temperature indicated in the Examples which follow and the hydrogenation is carried out under the hydrogen pressure indicated in the Examples until no further hydrogen is taken up.