Ammonia → 4-Nitro-4'-amino-stilbene-2,2'-disulphonic acid

Beteiligte Stoffe

Reaktionsschritte

An aqueous solution of the disodium salt of 4,4'-dinitro-stilbene-2,2'-disulphonic acid is treated with an equivalent amount, relative to the nitro group to be reduced, of sodium bisulphide solution at 75°-85° C., ammonia being added. The course of the reaction can be followed by known analytical methods. When the partial reduction has ended, the 4-nitro-4'-amino-stilbene-2,2'-disulphonic acid formed is isolated as the disodium salt or as an inner salt. The amount of 4,4'-diamino-stilbene-2,2'-disulphonic acid contained as an impurity is less than 1% and the residual content of 4,4'-dinitro-stilbene-2,2'-disulphonic acid is less than 0.1%. 4-Nitro-4'-aminostilbene-2,2'-disulphonic acid is a known intermediate product for dyestuffs.

Herkunft & Nachweise