Kinetics and Mechanism of Palladium(II)-Catalyzed Oxidation of Inositol by Hexachloroplatinate(IV) in Perchlorate Solutions

Abstract

Oxidation of inositol (INOS) by hexachloroplatinate(IV) complex (HCP) in perchlorate solutions in the presence of palladium(II) catalyst was studied spectrophotometrically. The reaction rate was very slow in the absence of the catalyst. The reaction exhibited a first order dependence on [HCP], and fractional-first order dependences with respect to [INOS], [H + ] and [Pd(II)]. Increasing ionic strength and dielectric constant was found to increase the oxidation rate. A probable oxidation mechanism has been suggested and the rate-law expression has been derived. Both spectral and kinetic evidences revealed formation of a 1:1 intermediate complex between INOS and Pd(II) prior to the rate-controlling step. The final oxidation product of inositol was identified by both spectral and chemical analyses as the corresponding monoketone derivative, namely inosose. The activation parameters of the second order rate constant were evaluated and discussed.