Electrochemical Behaviours of Substituted Thiophenes
No Thumbnail Available
Date
2000-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa,University
Abstract
The electrochemical oxidation of 3-methylthiophene, thiophene and 2',5'- dibtyloxy-3-
phenylthiophene have been studied using plalinium, glassy carbon and gold electrodes
in acetonitrile. Lithium perchlorate served as supporting electrolyte in all experiments.
The oxidation of 3-methyl thiophene at different concentration was carried out on Pt,
GC and Au electrodes using de cyclic voltammetry. As the concentration increases, a
preadsorption peak was noted in all electrodes. It was seen that the PI electrode is
more sensitive to the adsorpt ion of the product (radicals). The oxidation of 3-
methylthiophene was also performed under potentiastatic conditions. It was observed
that the current response decays with time at a rotating electrode. This shows that
diffusion is not a rate determining step in the oxidation of 3-methylthiophene.
The limiting charge passed on stationary and rotating Pt electrode was evaluated on
the primary oxidation of 4.2 mmol L-1 3-methylthiophene on Pt electrode. Attempts were
made to compare the charge passed with the theoretically charge expected from the
monola/ er coverage of the electrode surface.
The diffusion coefficient of ferrocene was determined on stationary Pt electrode. This
value was compared with that of 3-methylthiophene and thiophene. The higher value
of the diffusion coefficient of thiophene and 3-methylthiophene was due to a smaller
molecular radius.
In the electrochemical oxidation of 2',5'-dibutyloxy-3-phenylthiophene at least three
anodic oxidation peaks were observed in both DC and AC cyclic voltammetry. The first
peak potential occurred around 1.05 V, the second at 1.47 Vand the third around
1.91 V.
Description
Keywords
Electrochemical Behaviours