Synonyms: sodium 2,5-dichloro-4-[4,5-dihydro-3-methyl-4-[[4-[(p-tolylsulphonyl)oxy]phenyl]azo]-5-oxo-1H-pyrazol-1-yl]benzenesulphonate;Benzenesulfonic acid, 2,5-dichloro-4-4,5-dihydro-3-methyl-4-4-(4-methylphenyl)sulfonyloxyphenylazo-5-oxo-1H-pyrazol-1-yl-, sodium salt;2,5-Dichloro-4-[[4,5-dihydro-3-methyl-4-[[4-[[(4-methylphenyl)sulfonyl]oxy]phenyl]azo]-5-oxo-1H-pyrazol]-1-yl]benzenesulfonic acid sodium salt