Kinetics and mechanism of the oxidation of lower oxyacids of phosphorus byhexamethylenetetramine bromine

The oxidation of lower oxyacids of phosphorus by hexamethylenetetramine bro mine (HABR) in glacial acetic acid resulted in the formation of correspondi ng oxyacids with phosphorus in a higher oxidation state. The reaction exhib ited 2: 1 stoichiometry. The reaction is first order with respect to HABR. Michaelis-Menten-type kinetics were observed with respect to the acids. The formation constant of the phenylphosphinic acid-HABR complex also has been determined spectrophotometrically. The thermodynamic parameters For the co mplex formation and the activation parameters for their decomposition were calculated. The reaction showed the presence of a substantial kinetic isoto pe effect. It is proposed that the HABR itself is the reactive oxidizing sp ecies. It has been shown that the pentacoordinated tautomer of the phosphor us oxyacid is the reactive reductant. A suitable mechanism has been propose d. (C) 2000 John Wiley & Sons, Inc.