Synonyms: sodium 2,5-dichloro-4-[4,5-dihydro-4-[(4-hydroxyphenyl)azo]-3-methyl-5-oxo-1H-pyrazol-1-yl]benzenesulphonate;2,5-Dichloro-4-(dihydro-3-methyl-4-((4-hydroxyphenyl)azo)-5-oxo-1H-pyrazol-1-yl)benzenesulfonic acid, monosodium salt;2-Pyrazolin-5-one, 1-(2,5-dichloro-4-sulfophenyl)-4-((p-hydroxyphenyl)azo)-3-methyl-, sodium salt;Benzenesulfonic acid, 2,5-dichloro-4-(4,5-dihydro-4-((4-hydroxyphenyl)azo)-3-methyl-5-oxo-1H-pyrazol-1-yl)-, monosodium salt;Benzenesulfonic acid, 2,5-dichloro-4-(4,5-dihydro-4-(2-(4-hydroxyphenyl)diazenyl)-3-methyl-5-oxo-1H-pyrazol-1-yl)-, sodium salt (1:1);Einecs 267-545-6;Sodium 2,5-dichloro-4-(4,5-dihydro-4-((4-hydroxyphenyl)azo)-3-methyl-5-oxo-1H-pyrazol-1-yl)benzenesulphonate