Kinetics and Mechanism of the Oxidation of Phosphinic, Phenylphosphinic, and Phosphorous Acids by Pyridinium Fluorotrioxochromate(VI)

Article abstract of DOI:10.1039/DT9900002697

Oxidation of the lower phosphorus oxyacids by results in the formation of corresponding oxyacids in the higher valence states.The reaction is first order with respect to the oxidant concentration.A Michaelis-Menten type kinetics was observed with respect to the substrate, indicating the formation of a complex in a pre-equilibrium.The formation constants and the rates of disproportionation of the complexes have been evaluated at different temperatures.The reaction exhibits a substantial primary kinetic isotope effect.The rates in 19 different organicsolvents have been analysed using Kamlet-Taft and Swain equations.It has been found that the cation-solvating power of the solvents plays an important role.It is proposed that the 'inactive ' tautomer of the phosphorus oxyacids is the reactive reductant, and that transfer of a hydride ion from the P-H bond to the oxidant in the rate-determining step occurs.

Full text of DOI:10.1039/DT9900002697

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