Synthesis of 5',5"-Dichloro-3', 3"-disulphanilylamidophenolphthalein

Sulphonamidochlorophthaleins have been synthesised with a view to studying their pharmacological properties. Phenophthalein on nitration yields 3`,3'-dinitropherolphthalein which on chlorination, followed by reduction. provides 5',5"-dichloro-3',3'’-diaminophenolphthalein. The latter on condensation with N­acetylsulphanilyl chloroide (ASC) affords a product which on hydrolysis yields 5',5'’-dichloro-3',3'’-disulph. anilylamidophenolphthalein.