Disodium NaPhthalene-l, 4, 5, 8-tetracarboxylic Acid 4, 5-p-Sulfophenylimide (III). In a flask fitted with a stirrer, and reflux condenser were mixed two solutions:" i) 30 g of purified naphthalene-l, 4, 5, 8-tetracarboxylic acid and 8.8 g of NaOH in 550 ml of water, and 2) 17.3