Formation and redox properties of radical ions of iodopentafluorobenzene in aqueous solution: a pulse radiolysis study

Mohan, Hari ; Mittal, Jai P. (1995) Formation and redox properties of radical ions of iodopentafluorobenzene in aqueous solution: a pulse radiolysis study Journal of Physical Chemistry, 99 (33). pp. 12559-12564. ISSN 0022-3654

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Official URL: http://pubs.acs.org/doi/abs/10.1021/j100033a031

Related URL: http://dx.doi.org/10.1021/j100033a031

Abstract

The transient optical absorption bands λmax = 290 and 400 nm) formed on reaction of OH radicals in neutral aqueous solution of iodopentafluorobenzene are assigned to the phenoxyl radical. The radical decays by second-order kinetics with 2k/εl = 4.2 × 106 s-1 and results in the formation of F- and I- [G(F-) = 5.3, G(I-) = 0.2]. The rate constant for the reaction of OH radical with iodopentafluorobenzene is 1.1 × 109 dm3 mol-l s-1. In acidic solution ([HClO4] < 1 mol dm-3, the nature of the transient optical absorption spectrum remained the same whereas when [HClO4] > 1 mol dm-3, the transient optical absorption bands formed at 310 and 660 nm are assigned to the solute radical cation. Cl2•- radical anion is unable to undergo electron transfer reaction with C6F5I whereas SO4•- radical anion is able to react with a bimolecular rate constant of 3.3 × 108 dm3 mol-1 s-1, and transient bands observed at 290 and 390 nm are assigned to the phenoxyl radical. The solute radical cation is a powerful one-electron oxidant and is able to oxidize a number of organic compounds with high rate constant values. The hydrated electron reacts with C6F5I by a nondissociative electron capture process, and the resulting radical anion undergoes fast protonation to form the cyclohexadienyl radical (λmax) = 290 mm). The bimolecular rate constant for the reaction of eaq - with C6F5I was 8 × 109 dm3 mol-1 s-1. Similar transient species is also observed on reaction of CO2•- radical anion with C6F5I. The spectrum of the radical anion is not observed even at pH 14.

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Source:Copyright of this article belongs to American Chemical Society.
ID Code:25727
Deposited On:04 Dec 2010 11:49
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