Kinetic study of 2-propanol and benzyl alcohol oxidation by alkaline hexacyanoferrate(III) catalyzed by a terpyridyl ruthenium complex

The complex (Trpy)RuCl3 (Trpy = 2,2':6',2"-terpyridine) reacts with alkaline hexacyanoferrate(III) to form a terpyridyl ruthenium(IV)-oxo complex that catalyzes the oxidation of 2-propanol and benzyl alcohol by alkaline hexacyanoferrate(III). The reaction kinetics of this catalytic oxidation have been studied photometrically. The reaction rate shows a first-order dependence on [Ru(IV)], a zero-order dependence on [hexacyanoferrate(III)], a fractional order in [substrate], and a fractional inverse order in [HO-]. The kinetic data suggest a reaction mechanism in which the catalytic species and its protonated form oxidize the uncoordinated alcohol in parallel slow steps. Isotope effects, substituent effects, and product studies suggest that both species oxidize alcohol through similar pericyclic processes. The reduced catalytic intermediates react rapidly with hexacyanoferrate(III) and hydroxide to reform the unprotonated catalytic species. (C) John Wiley & Sons, Inc.