2,7-Naphthalenedisulfonic acid, 4,5-dihydroxy-3-[[4'-[(1-hydroxy-4-sulfo-2-naphthalenyl)azo]-3,3'-dimethyl[1,1'-biphenyl]-4-yl]azo]-, trisodium salt 5442-09-1 C.I. 23690 C.I. Direct Blue 31 C.I. Direct Blue 31, trisodium salt Dianil Blue 2R Dianil blue Direct Blue 2R NSC8678