Chromium, 2,4-dihydro-4-[(2-hydroxy- 5-nitrophenyl)azo]-5-methyl-2-phenyl-3H-pyrazol-3 -one 3-[(4,5-dihydro-3-methyl- 5-oxo-1-phenyl-1H-pyrazol-4-yl)azo]-4-hydroxybenzenesulfonamide 4-hydroxy-3-[(2-hydroxy-1- naphthalenyl)azo]benzenesulfonamide N-[7-hydro