Thermal and Spectrophotometric Studies of 8-Mercaptoquinoline-5-sulfonic Acid and Its Sodium Salt

Publisher Website
Google Scholar
Abstract
Thermal and spectrophotometric studies of 8-mercaptoquinoline-5-sulfonic acid and its sodium salt synthesized by an improved method are reported. In order to determine the best formula for the weighing of organic reagent, the thermal stabilities of 8-mercaptoquinoline-5-sulfonic acid and its sodium salt and the amount of water of crystallization were examined with a thermal balance. It was found that the disodium dihydrate was of the best form. The ultraviolet and visible absorption spectra in aqueous-ethanol solution were measured, the tauto-meric constant Kt between neutral and zwitterion forms being estimated and acid dissociation constants obtained spectrophotometrically. The absorption spectra and the equilibrium constants of the reagents were compared with those of 8-mercaptoquinoline, 8-hydroxyquinoline and 8-hydroxyquinoline-5-sulfonic acid.