5-[(4,5-dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl)azo]-6-hydroxynaphthalene-1-sulphonic acid

5-[[(4,5-Dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol)-4-yl]azo]-6-hydroxy-1-naphthalenesulfonic acid