Kinetics and mechanism of oxidation of phosphorus oxyacids by pyridinium hydrobromide perbromide

摘要: Oxidation of three lower oxyacids phosphorus, viz. phosphinic, phenylphosphinic and phosphorous acids by pyridinium hydrobromide perbromide (PHPB), is first-order with respect to both oxyacid PHPB. There no effect on addition acylonitrile bromide. On oxidation, deuterated phosphinic exhibit substantial kinetic isotope effects. The solvent composition reaction rate indicates that the transition state more polar than reactants. Reaction rates were determined at different temperatures activation parameters calculated. Alternative mechanisms, involving two tautomeric forms oxyacid, have been formulated it has concluded proceeds through pentacoordinated tautomer. Transfer a hydride ion from PHPB, in rate-determining step, proposed.