Synonyms: 2,7-Naphthalenedisulfonic acid, 4-hydroxy-5-(((4-methylphenyl)sulfonyl)amino)-3-(2-phenyldiazenyl)-, compd. with N,N'-bis(2-methylphenyl)guanidine (1:2);2,7-Naphthalenedisulfonic acid, 4-hydroxy-5-(((4-methylphenyl)sulfonyl)amino)-3-(phenylazo)-, compd. with N,N'-bis(2-methylphenyl)guanidine (1:2);4-Hydroxy-3-(phenylazo)-5-(((p-tolyl)sulphonyl)amino)naphthalene-2,7-disulphonic acid, compound with N,N'-di(o-tolyl)guanidine (1:2);(3Z)-5-{[(4-methylphenyl)sulfonyl]amino}-4-oxo-3-(2-phenylhydrazinylidene)-3,4-dihydronaphthalene-2,7-disulfonic acid - 1,2-bis(2-methylphenyl)guanidine (1:2)