2,3-Dihydro-3-oxo-2-(4-sulfobenzylidene)benzo(b)thiophene-6-sulfonic acid, dipotassium salt 68516-62-1 Benzo(b)thiophene-6-sulfonic acid, 2,3-dihydro-3-oxo-2-((4-sulfophenyl)methylene)-, dipotassium salt Dipotassium 2,3-dihydro-3-oxo-2-((4-sulphonatophenyl)methylene)benzo(b)thiophene-6-sulphonate EINECS 271-167-7