Studies on protonation and Th(IV) complexation behaviour of dihydroxybenzenes in aqueous 1 M NaClO4 medium

摘要

Complexing behaviour of three dihydroxybenzenes (DHB) namely, hydroquinone, resorcinol and catechol with Th(IV) along with their protonation constants were studied in 1 M NaClO4 medium at 23 +/- 0.5 degrees C, using pH titration technique. Both protonation and metal-ligand equilibrium constants of dihydroxybenzenes were computed using advance software suite of program HYPERQUAD. Logarithmic values of overall protonation constants (109 beta(1H) and log beta(2H)) were found to be 11.47 +/- 0.05 and 21.45 +/- 0.06, for hydroquinone, 11.76 +/- 0.04 and 20.98 +/- 0.04 for resorcinol and 12.58 +/- 0.03 and 21.87 +/- 0.08 for catechol respectively. Complex formation has been investigated in the pH range 2 to 4. The logarithmic values of metal-ligand equilibrium constants obtained in the present work were beta(13-1) = 48.51 +/- 0.67 and beta(14-1) = 64.86 +/- 1.25 for hydroquinone, beta(110) = 16.98 +/- 0.16, beta(13-1) = 46.46 +/- 0.18 and beta(14-2) = 59.65 +/- 0.20 for resorcinol and beta(11-1) = 14.06 +/- 0.10 for catechol. The literature values were reviewed.