(1,1'-Biphenyl)-2,2'-disulfonic acid, 4-((4,5-dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl)azo)-4'-((2-hydroxy-1-naphthalenyl)azo)-, disodium salt 6470-20-8 C.I. Acid Orange 56 Disodium 4-((4,5-dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl)azo)-4'-((2-hydroxy-1-naphthyl)azo)(1,1'-biphenyl)-2,2'-disulphonate EINECS 229-294-0