The molecule is a member of the class of azobenzenes that is azobenzene in which one of the phenyl groups is substituted at the para position by a sulfo group, while the other is substituted at a meta position by a sulfo group and at the para position by an amino group. The disodium salt is the biological stain 'fast yellow'. It is a member of azobenzenes, an amino sulfonic acid and a primary arylamine. It is a conjugate acid of a 4-aminoazobenzene-3,4'-disulfonate.
2-amino-5-[(4-sulfophenyl)diazenyl]benzenesulfonic acid