sodium 4-chloro-3-[4,5-dihydro-4-[(2-hydroxy-4-nitrophenyl)azo]-3-methyl-5-oxo-1H-pyrazol-1-yl]benzenesulphonate

4-Chloro-3-[[4,5-dihydro-4-[(2-hydroxy-4-nitrophenyl)azo]-3-methyl-5-oxo-1H-pyrazol]-1-yl]benzenesulfonic acid sodium salt