Kinetics and mechanism of oxidation of lower oxyacids of phosphorus by tetrabutylammonium tribromide

Abstract

Oxidation of lower oxyacids of phosphorus by tetrabutylammonium tribromide (TBATB) in aqueous acetic acid leads to the formation of corresponding oxyacids with phosphorus in a higher oxidation state. The reaction exhibits 1:1 stoichiometry. The reaction is first order each in [TBATB] and [oxyacids]. The

reaction does not induce polymerization of acrylonitrile. There is no effect of tetrabutylammonium chloride on the reaction rate. The proposed reactive oxidizing species is tribromide ion. It has been shown that the pentacoordinated tautomer of the phosphorus oxyacid is the reactive reductant. The oxidation of deuteriated oxyacids exhibit s a substantial primary kinetic isotope effect. The

effect of solvent composition indicates that the rate increases with an increase in the polarity of the solvent. A mechanism involving transfer of a hydride ion in the rate-determining step has been proposed.