The absorption spectrum and dissociation constants of 4-hydroxybenzthiazole

The absorption spectra of 4-hydroxybenzthiazole and the parent compound, benzthiazole, have been determined in acidic, basic and neutral solutions, and compared with the corresponding absorption spectra of 8-hydroxyquinoline and quinoline. The dissociation constants of 4-hydroxybenzthiazole obtained by a spectrophotometric method as well as a potentiometric method, show that it is a stronger acid and a weaker base than 8-hydroxyquinoline.