tetrasodium 7,7'-[ureylenebis[(2-methyl-p-phenylene)azo]]dinaphthalene-1,3-disulphonate

7,7'-[Ureylenebis[(2-methyl-4,1-phenylene)azo]]bis(1,3-naphthalenedisulfonic acid disodium) salt

1,3-Naphthalenedisulfonic acid, 7,7'-[iminobis[carbonyl(2- methyl-4,1-phenylene)azo]]bis-, tetrasodium salt