a method of preparing aromatic amines by reduction of aromatic nitro compounds:
ArNo2 + 3H2S → ArNH2 + 3S + 2H2O
The reaction was discovered in 1842 by N. N. Zinin, using as an example the reduction of α-nitronaphthalene and nitro-benzene to α-aminonaphthalene and aniline, respectively [the reducing agents were H2S or (NH4)2S]. He subsequently showed the reaction to be of general application. The principle of the Zinin reaction is the basis for the synthesis of numerous aromatic amines, many of which are the initial materials for the synthesis of dyes, Pharmaceuticals, explosives, perfumes, and medicinal substances. The extensive application of the Zinin reaction to a considerable degree determined the path of development of organic synthesis.
Later, cast-iron filings and acid began to be used for reducing organic nitro compounds. However, ammonium sulfide, which Zinin used as a reducing agent, retained some importance for making anthraquinone amines, and mainly for particle reduction of dinitro and polynitro compounds.