Abstract
The reduction and oxidation potentials of methylated 4-styrylpyrylium and 6-styrylpyrylium perchlorates have been evaluated using cyclic voltammetry, in comparison to their non-methylated derivatives values. The reduction peak of all studied compounds remained chemically irreversible. The presence of the electron-donating methyl group on pyrylium ring leads to a shift of the styrylpyrylium perchlorates reduction potential towards cathodic values. Kinetic studies on platinum electrodes based on the variation of the peak potential at different scan rates and upon substrate concentrations confirm, in another way, the mechanism of electron transfer. KEY WORDS : Styrylpyrylium perchlorates, Cyclic voltammetry, Reduction potential, Kinetic study Bull. Chem. Soc. Ethiop. 2013 , 27(1), 117-124. DOI: http://dx.doi.org/10.4314/bcse.v27i1.12
Highlights
Pyrylium cations are oxonium ions widely used as reactive intermediates in many organic syntheses [1, 2]
It is admitted that pyrylium cation submitted to reduction in aprotic solvent, evolves according to a one-electron transfer to lead to a pyranyl radical which can evolve through dimerization process to give a bispyranic product [12,13,14]
We report the potential reduction values obtained by cyclic voltammetry of two methylated styrylpyrylium perchlorates in comparison with the potential reduction values of non-methylated styrylpyrylium perchlorates previously determined by Guel et al [17]
Summary
Pyrylium cations are oxonium ions widely used as reactive intermediates in many organic syntheses [1, 2]. E-mail: bonziy@univ-ouaga.bf kinetic study in electrochemistry, based on the effect of substrate concentration and scan rate on the reduction peak potential, to determine the real reduction mechanism of the styrylpyrylium perchlorates derivatives. RESULTS AND DISCUSSION Electrochemical reduction of methylstyrylpyrylium perchlorates Figure 1 shows the voltammetric behavior of the styrylpyryliums 1b and 1d investigated in acetonitrile containing 0.1 M of tetrabutylammonium hexafluorophosphate (Bu4NPF6) as the supporting electrolyte.
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