(1,1'-Biphenyl)-2,2'-disulfonic acid, 4,4'-bis((2-hydroxy-1-naphthalenyl)azo)-5,5'-dimethyl-, disodium salt 6472-50-0 Disodium 4,4'-bis((2-hydroxy-1-naphthyl)azo)-5,5'-dimethyl(1,1'-biphenyl)-2,2'-disulphonate EINECS 229-321-6