2-Hydroxy-5-[[5-hydroxy-6-[(2-sodiooxycarbonylphenyl)azo]-7-sodiosulfo-2-naphthalenyl]azo]benzoic acid sodium salt

2-Aminobenzoic acid diazo, in alkaline conditions and 7-Amino-4-hydroxynaphthalene-2-sulfonic acid coupling, its product to diazo, coupled with 2-Hydroxybenzoic acid.

Dark purplish red. Soluble in water for red, and adequate soluble in alcohol. In the dark for the strong sulfuric acid, diluted as a pale orange-red to brown. The dye solution to join strong hydrochloric acid have red light brown precipitation; Add sodium hydroxide to red light brown.