disodium 4-hydroxy-6-(phenylamino)-3-[(4-sulphonatophenyl)azo]naphthalene-2-sulphonate

4-Aminobenzenesulfonic acid?diazo, in alkaline conditions and 4-Hydroxy-6-(phenylamino)naphthalene-2-sulfonic acid coupling.

dark red light brown. Soluble in water, soluble in ethanol in very small amounts of red brown. The strong sulfuric acid for red, for orange brown after diluted. In water solution to join strong hydrochloric acid for brown; Add thick sodium hydroxide solution for red wine.