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The Effect of Adsorption Conformation of Intermediates on Kinetic Parameters of Electrode Reactions. Mechanism of the Electroreduction of Dihalopyridines on the DME
Author(s) -
KashtiKaplan S.,
KirowaEisner E.
Publication year - 1979
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.197900008
Subject(s) - chemistry , tafel equation , adsorption , electrode , protonation , inorganic chemistry , reaction mechanism , kinetic energy , reaction intermediate , electrochemistry , catalysis , organic chemistry , ion , physics , quantum mechanics
The mechanism of reduction of 2,6‐dichloropyridine, 2,5‐dibromopyridine and 2,3‐dichloropyridine in ethanol‐water media was investigated at the DME. The electrode processes were studied by measurements of Tafel slopes, reaction orders and pH effects. The proposed mechanism involves: (i) first protonation and electronation in a quasi‐equilibrium step resulting in an adsorbed pyridinyl radical (intermediate I ) parallel to the electrode surface, (ii) Cleavage of the C–X bond in the rate‐determining step, resulting in an adsorbed cation radical (intermediate II ), perpendicular to the electrode. The Tafel slope computed via the combined‐adsorption isotherm are in agreement with the experimental values.