trisodium 4-[[7-[(2,4-diaminophenyl)azo]-1-hydroxy-3-sulphonato-2-naphthyl]azo]-4'-[(4-hydroxyphenyl)azo][1,1'-biphenyl]-2,2'-disulphonate

2,2′-Disulfo-4,4,diaminobibenzene double nitriding, first with phenol?, and then in three alkaline conditions and 6-Amino-4-hydroxynaphthalene-2-sulfonic acid? coupling, product to diazo, and Benzene-1,3-diamine coupling.

red light brown. Soluble in water for brown. The strong sulfuric acid in light color for palm red, red light brown after diluted precipitation. The dye solution to join strong hydrochloric acid have red light brown precipitation; Add thick sodium hydroxide solution is palm red light.