Preparation
4-Amino-N-(4-aminophenyl)benzenesulfonamide double nitriding.sulfonylurea aniline, in alkaline conditions and 4-Amino-5-hydroxynaphthalene-2,7-disulfonic acid?coupling, 4-Nitrobenzenamine diazo, in acid conditions and the above the products of coupling, and Benzene-1,3-diamine coupled.