Oxidation Kinetics of some Lower Oxyacids of Phosphorus by Picolinium Chlorochromate: Determination of Reactive Reducing Species

Abstract

Picolinium chlorochromate (PICC) in dimethylsuloxide (DMSO) oxidizes lower oxyacids of phosphorus, forming matching oxyacids with phosphorus in a higher oxidation state. The reaction shows a stoichiometry of 1:1. In relation to PICC, the response is first order. Regarding the reductants, a kinetics of the Michaelis-Menten type was noticed. Acrylonitrile does not undergo polymerization as a result of the reaction. Hydrogen ions function as catalysts for reactions. The form of the hydrogen-ion dependency is: kobs = a + b[H+]. Deuterated phosphinic and phenylphosphinic acids showed a significant primary kinetic isotope impact during oxidation. Nineteen different organic solvents were used to study the oxidation. The multiparametric equations of Taft and Swain were used to analyze the solvent effects. The influence of the solvent shows that the polarity of the solvent is crucial to the process. The penta-coordinated tautomer of the phosphorus oxyacid has been shown to be the reactive reductant, and it has been determined that the tricoordinated forms of phosphorus oxyacids do not take part in the oxidation process. It has been hypothesized that the rate-determining phase involves the transfer of a hydride ion.