Chlorine Dioxide as an Electron-Transfer Oxidant of Olefins

Article abstract of DOI:10.1002/hlca.19860690729

The kinetics and product studies of oxidation of eight olefins 1-8 by ClO2 in H2O in the pH range 3-7 are described.The reaction is faster as the pH decreases.At pH<4, ClO2 reacts equimolarly with olefins to yield isomeric mixtures of chlorohydrines and 1,2-dioxygenated products, following the equation: The order of reactivity is: (E)-stilbene > indene > β-methylstyrene > acenaphthylene > α-methylstyrene > styrene > cyclohexene > allylbenzene.A multi-stage radical-cation mechanism is proposed, in which an initial reversible protonation: is followed by an electron-transfer stage (rate-determining): The cation-radical thus produced, adds rapidly an additional ClO2 to from dioxygenated products.The chlorohydrines most likely arise from HClO additions to the olefinic double bonds, which, in turn, generate from dismutation of 2HClO2 into HClO + H⁺ + ClO3^-.