Synonyms: 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-(2-(4-(2-phenyldiazenyl)phenyl)diazenyl)-, compd. with N,N'-bis(2-methylphenyl)guanidine (1:2);7-Hydroxy-8-((p-(phenylazo)phenyl)azo)-1,3-naphthalenedisulfonic acid, compd. with 1,3-di-o-tolylguanidine (1:2);1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-(phenylazo)phenyl)azo)-, compd. with N,N'-bis(2-methylphenyl)guanidine (1:2);7-Hydroxy-8-((4-(phenylazo)phenyl)azo)naphthalene-1,3-disulphonic acid, compound with N,N'-di(o-tolyl)guanidine (1:2);(8Z)-7-oxo-8-(2-{4-[(E)-phenyldiazenyl]phenyl}hydrazinylidene)-7,8-dihydronaphthalene-1,3-disulfonic acid - 1,2-bis(2-methylphenyl)guanidine (1:2)