Preparation
4-Nitrobenzenamine diazo, in alkaline conditions and 4-Amino-5-hydroxynaphthalene-2,7-disulfonic acidcoupling, its product to diazo, Coupled with resorcinol, product again with diazo of 4-Nitrobenzenamine and 5-Amino-2-(phenylamino)benzenesulfonic acid coupling.
