3-[[4-[(2,4-Diaminophenyl)azo]phenyl]azo]-6-[(2,4-diamino-5-sulfophenyl)azo]-4-hydroxy-2-naphthalenesulfonic acid disodium salt

N-(4-aminophenyl)acetamide diazo, in alkaline conditions and 6-Amino-4-hydroxynaphthalene-2-sulfonic acid?, amino, acylation coupled hydrolysis product to double nitriding, which in turn and Benzene-1,3-diamine and 2,4-Diaminobenzenesulfonic acid coupling.

black.