2-Naphthalenesulfonic acid, 4-hydroxy-3-[(2-methoxyphenyl)azo]-6-[(2-sulfoethyl)amino]-, disodium salt

O-Anisidine diazo, in alkaline conditions and 4-Hydroxy-6-(2-sulfoethylamino)naphthalene-2-sulfonic acid?coupling.

Dark time Soluble in water for red brown, the solubility in ethanol is very small. The strong sulfuric acid for purple, diluted into pink. In water solution to join strong hydrochloric acid is palm orange; Add thick sodium hydroxide solution by red to product red.