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Chlorine Dioxide as an Electron‐Transfer Oxidant of Olefins. Preliminary Communication
Author(s) -
RavAcha Chaim,
Choshen Goldstein Ehud,
Sarel Shalom
Publication year - 1986
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19860690729
Subject(s) - chemistry , cyclohexene , indene , electron transfer , styrene , photochemistry , acenaphthylene , protonation , reactivity (psychology) , yield (engineering) , kinetics , medicinal chemistry , chlorine , alkene , organic chemistry , ion , naphthalene , catalysis , copolymer , medicine , polymer , alternative medicine , materials science , physics , pathology , quantum mechanics , metallurgy
The kinetics and product studies of oxidation of eight olefins 1 ‐ 8 by ClO 2 in H 2 O in the pH range 3‐7 are described. The reaction is faster as the pH decreases. At pH < 4, ClO 2 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:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm ClO}_{{\rm 2}} + {\rm H}^{\rm +} \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} \left[{{\rm HClO}_{\rm 2}} \right]^ + $$\end{document}is followed by an electron‐transfer stage (rate‐determining):The cation‐radical thus produced, adds rapidly an additional ClO 2 to form dioxygenated products. The chlorohydrines most likely arise from HClO additions to the olefinic double bonds, which, in turn, generate from dismutation of 2 HClO 2 into HClO + H + + ClO 3 − .