Kinetics and mechanism of oxidation of phosphinic, phenylphosphinic and phosphorous acids by 2,2' -bipyridinium chlorochromate

Abstract

The title reaction is of second order, first with respect to the each reactant. The reaction is catalysed by hydrogen ions; the hydrogen ion dependence the form <em>k</em>_obs = a +b [H⁺]. The oxidation of phosphinic and phosphorous acids exhibits a substantial primary kinetic isotope effect. The reaction has been studied in nineteen organic solvents and the effect of solvent is analysed using Taft's and Swain's multiparametric equations. The participation of the tautomeric forms of the phosphorus oxyacids, in the oxidation process, has been discussed. It has been concluded that the tri-coordinated form of the phosphorus oxyacids does not participate in the oxidation process. A suitable mechanism has been proposed.