Synonyms: Benzenesulfonic acid, 3,3'-((4,6-dihydroxy-1,3-phenylene)bis(2,1-diazenediyl))bis-, compd. with N,N'-bis(2-methylphenyl)guanidine (1:2);3,3'-((4,6-Dihydroxy-m-phenylene)diazo)dibenzenesulphonic acid, compound with N,N'-di(o-tolyl)guanidine (1:2);Benzenesulfonic acid, 3,3'-((4,6-dihydroxy-1,3-phenylene)bis(azo))bis-, compd. with N,N'-bis(2-methylphenyl)guanidine (1:2);3-[(2Z)-2-{4-hydroxy-6-oxo-3-[(E)-(3-sulfophenyl)diazenyl]cyclohexa-2,4-dien-1-ylidene}hydrazinyl]benzenesulfonic acid - 1,2-bis(2-methylphenyl)guanidine (1:2)