4-Hydroxy-3-[[4'-[(1-hydroxy-6-phenylamino-3-sodiosulfo-2-naphthalenyl)azo]-1,1'-biphenyl-4-yl]azo]naphthalene-2,7-disulfonic acid disodium salt

4-(4-Aminophenyl)benzenamine double nitriding, first with 4-Hydroxynaphthalene-2,7-disulfonic acid coupling, again in alkaline conditions and 4-Hydroxy-7-(phenylamino)naphthalene-2-sulfonic acid coupling.

Dark blue purple. Soluble in water for purplish red, slightly soluble in ethanol for pink. The strong sulfuric acid in blue, diluted for dark purple. The dye solution to join strong hydrochloric acid for Red sauce, precipitation; Add thick sodium hydroxide solution for red light brown.

Standard	Acid Resistance	Alkali Resistance	Light Fastness	Soaping		Water
				Fading	Stain	Fading	Stain
ISO	4	4-5	2	2		2