Palladium(II)-Catalyzed Oxidation of Pyrimidine Derivative by Hexacyanoferrate(III) in Aqueous Alkaline Medium: A Kinetic Study

The of kinetics of oxidation of a pyrimidine derivative, N,N-dimethyl-N’-(pyrimidin-2-yl) formamidine (Pym-F), by hexacyanoferrate(III) (HCF) was studied in aqueous alkaline medium in the presence of palladium(II) catalyst. The reaction did not proceed in the absence of Pd(II) catalyst. The progress of the catalyzed reaction was followed spectrophotometrically. The reaction showed a first order kinetics in both [HCF] and [Pd(II)], and less than unit orders with respect to both [Pym-F] and [OH-]. Increasing ionic strength and dielectric constant of the medium increased the reaction rate. A mechanistic scheme for the catalyzed oxidation reaction has been proposed. The final oxidation products are identified as 2-aminopyrimidine, dimethylamine and carbon dioxide. The rate law expression associated with the reaction mechanism is derived and the reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to the rate-determining step have been computed and discussed.