Untersuchungen zur Kinetik der anodischen Oxydation von Anilin in Azetonitril an der rotierenden Platinelektrode
In the present work, the anodic oxidation of aniline at a rotating platinum disc electrode was studied in acetonitrile as solvent. The half-wave potential is +860 mV vs. SCE. The number of electrons transferred in the rate-determining step is two. Electrolysis under potentiostatic conditions also ga... Ausführliche Beschreibung
|1. Person:||Breitenbach, M.|
|Weitere Personen:||Heckner, K.H.|
in Journal of Electroanalytical Chemistry Vol. 29, No. 2 (1971), p. 309-323
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Copyright: Copyright (c) 2006 Elsevier B.V.
In the present work, the anodic oxidation of aniline at a rotating platinum disc electrode was studied in acetonitrile as solvent. The half-wave potential is +860 mV vs. SCE. The number of electrons transferred in the rate-determining step is two. Electrolysis under potentiostatic conditions also gave a two-electron transfer for the overall reaction. The electrochemical reaction order is one. The dependence of the limiting current on the rotation speed of the electrode satisfies the Levich equation. The aniline wave was increased by the addition of base (pyridine). From these facts certain conclusions can be drawn about the reaction mechanism. First, from a consideration of the effect of the base, it is possible to determine the true diffusion coefficient of aniline in acetonitrile as D=3.42x10^-^5 cm^2 s^-^1. This value is compared with values for other compounds. The experimental results lead to the following mechanism: After the primary one-electron oxidation of aniline to the radical cation, there follows a rapid deprotonation step. Then follows the further oxidation of the radical C"6H"5NH. Intermediates in the aniline oxidation are the dimers benzidine and p-aminodiphenylamine. They are further oxidized at potentials more negative than aniline itself and form highly condensed reaction products.