1,2-Benzenedicarboxylic acid, 4-sulfo-, monosodium salt 33562-89-9 4-Sulfophthalic acid monosodium salt 5-Sulfoisophthalic acid 5-sodium salt EINECS 251-572-5 Monosodium 4-sulfophthalate NSC 66547 Phthalic acid, 4-sulfo-, monosodium salt Sodium dihydrogen 4-sulphonatophthalate