Abstract: 4,4'-DIAMINOSTILBENE-2,2'-DISULFONIC ACID (HEREINAFTER ABBREVIATED AS DAS) or its alkali salt (abbreviated as DAS-salt) are prepared by catalytic hydrogenation of 4,4'-dinitrostilbene-2,2'-disulfonic acid (hereinafter abbreviated as DNS) or its alkali salt (abbreviated as DNS-salt). The catalytic hydrogenation is carried out using Raney nickel catalyst in the presence of dicyandiamide in water at a temperature in the range of 50.degree.-120.degree. C under an elevated hydrogen pressure. In both DNS-salt and DAS-salt alkali means sodium or potassium.

Abstract: Process for producing halogenated aromatic primary amines that may contain substituents such as methyl, ethyl, methoxy, and so on, by catalytic hydrogenation of halogenated aromatic nitro compounds in the presence both of a Raney nickel catalyst and of a dehalogenation inhibitor selected from the group consisting of dicyandiamide, cyanamide and calcium cyanamide, in an inert solvent at a temperature in the range from 40.degree. to 150.degree. C under an elevated hydrogen pressure, whereby any dehalogenated aromatic primary amine impurity in the halogenated aromatic primary amine product is held to an acceptable minimum so that the halogenated aromatic amines may be produced in a high state of purity.