hexasodium 6,6'-[vinylenebis[(3-sulphonato-4,1-phenylene)azo]]bis[4-amino-5-hydroxynaphthalene-1,3-disulphonate]

6,6'-[1,2-Ethenediylbis[(3-sodiooxysulfonyl-4,1-phenylene)azo]]bis[4-amino-5-hydroxy-1,3-naphthalenedisulfonic acid disodium] salt