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7918816 
Journal Article 
2,2,6,6-Tetramethyl piperidine-1-oxyl (TEMPO)-mediated catalytic oxidation of benzyl alcohol in acetonitrile and ionic liquid 1-butyl-3-methyl-imidazolium hexafluorophosphate [BMIm] [PF6]: Kinetic analysis 
Herath, AC; Becker, JY 
2008 
Yes 
Electrochimica Acta
ISSN: 0013-4686 
53 
12 
4324-4330 
English 
WOS:000255137500032 
TEMPO (2,2,6,6-tetramethyl piperidine-1-oxyl) is electrochemically oxidized to a stable form of the cation (TEMPO+) in acetonitrile (CH3CN) or 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIm][PF6]) media. Cyclic voltammograms were characterized by a well-defined one-electron reversible redox couple in both media at low scan rates. The reduced form of TEMPO+ is catalytically regenerated in a follow-up chemical reaction with benzyl alcohol (BA) in the presence of 2,6-lutidine. It was observed that in [BMIm][PF6], the redox currents are largely suppressed compared to that in CH3CN. The apparent heterogeneous electron-transfer rate constant (kapp0) of the quasi-reversible redox reaction of TEMPO was determined at a Pt electrode and found to be 1.9 × 10-3 cm s-1 and 4.5 × 10-2 cm s-1 in [BMIm][PF6] and CH3CN, respectively. With the aid of chronoamperometry (CA), the homogeneous rate constant for the catalytic oxidation of benzyl alcohol by TEMPO, in the presence of 2,6-lutidine in CH3CN was estimated to be 5.53 × 101 M-1 s-1 which is approximately double, relative to the value of 2.91 × 101 M-1 s-1 determined in [BMIm][PF6]. © 2008 Elsevier Ltd. All rights reserved. 
TEMPO; catalytic current; ionic liquid; benzyl alcohol; rate constant