Kinetics of basic hydrolysis of tris(1,10‐phenanthroline)iron(II) in macromolecular assemblies of CTAB

Abstract

AbstractThe kinetics of basic hydrolysis of tris(1,10‐phenanthroline)iron(II) has been carried out in aqueous, N‐cetyl‐N,N,N‐trimethyl ammonium bromide (CTAB) micellar, and CTAB reverse micellar media by UV–visible spectroscopy system. The reaction follows the overall second‐order kinetics; first order in each Fe(II) complex and the base (−OH). CTAB micelles catalyze the reaction rate through the adsorption of the Fe(II) complex and the hydroxyl ions on the micellar surface. In the reverse micellar medium, interesting physicochemical features are observed. Being ionic nature of reactants, both the reactants prefer to stay and react inside the water pool in place of the hydrophobic environment. The rate increases with w, that is, the size of the water pool, attains a maximum value at w = 8.33, and then decreases. But the rate increases as the concentration of surfactant increases at fixed w values. For a better explanation of the kinetic data, the activation parameters, standard enthalpy of activation (Δ‡H°), standard entropy of activation (Δ‡S°), and energy of activation (Ea) were determined. All kinetic data corroborate the proposed mechanism. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 579–589, 2011