Dissociation and coordinating ability of 1,2,3,4-tetrahydro-8-hydroxyquinoline in aqueous solution

The state of 1,2,3,4-tetrahydro-8-hydroxyquinoline is studied spectrophotometrically in the near-UV and visible regions at different pH in an aqueous solution in the presence and absence of Cu 2+ , Zn 2+ , and Cd 2+ cations. The dissociation constant (p K 1 ≈ 5.6 (293 K)) is (293 K)) is estimated from the pH-metric data. The stability of the complexes formed decreases in the series Cu 2+ > Zn 2+ ≥ Cd 2+ . The influence of tetrahydro atoms on the dissociation, complexation, and change in the state of 1,2,3,4-tetrahydro-8-hydroxyquinoline in an aqueous solution is discussed.