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Formation and Reaction of Br2-Radicals in the Ionic Liquid Methyltributylammonium Gis(trifluoromethylsufonyl)imide and in Other Solvents

Published

Author(s)

J Grodkowski, Pedatsur Neta

Abstract

Reaction of solvated electrons with BrCh2Ch2Br produces Br- and CH2CH2Br, which decomposes rapidly into CH2=CH2 and Br with Br2-. The stability of Br2- is much greater in the ionic liquid and in acetonitrile than in water or alcohols. The rate constant for oxidation of chlorpromazine by Br2- radicals decreases upon changing the solvent from water (nearly equal to} 6 x 109 L mol-1 s-1) to methanol (2.8 X 109 L mol-1 S-1), ethanol (1.2 x 109 L mol-1 s-1), 2 propanol (1.2 x 109 L mol-1 s-1), N-propanol (7.5 x 108 L mol-1 s-1), tert-butyl alcohol (3.0 x 108 L mol-1 s-1), acetonitrile (2.0 x 107 L mol-1), N, N-dimethylformamide (5.3 x 106 L mol-1 s-1), the ionic liquid methyltributylammonium bis(trifluoromethylsulfonyl)imide (1,1 x 106 L mol-1 s-1), and hexamethylphosphoramide (less then} 8 x 104 L mol-1 s-1). The rate constants show poor correlation with typical solvent polarity parameters but reasonable correlations with hydrogen bond donor acidity and with anion-solvation tendency parameters. From the good correlation with the free energy of transfer of Br- ions from water to the various solvents it is suggested that the change in the energy of solvation of Br- in the different solvent is the main factor that affects the rate constant of the reaction through its effect on the reduction potential of Br2- and the driving force of the reaction.
Citation
Journal of Physical Chemistry A
Volume
106
Issue
No. 46

Keywords

electron transfer, ionic liquids, pulse radiolysis, reaction kinetics, solvent effect

Citation

Grodkowski, J. and Neta, P. (2002), Formation and Reaction of Br<sub>2</sub><sup>-</sup>Radicals in the Ionic Liquid Methyltributylammonium Gis(trifluoromethylsufonyl)imide and in Other Solvents, Journal of Physical Chemistry A (Accessed April 18, 2024)
Created October 31, 2002, Updated October 12, 2021