1,2-Benzenedicarboxylic acid, 4-sulfo-, monosodium salt 33562-89-9 4-Sulfophthalic acid monosodium salt 5-Sulfoisophthalic acid 5-sodium salt Monosodium 4-sulfophthalate NSC66547 Phthalic acid, 4-sulfo-, monosodium salt