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Kinetic study of the oxidation of some catecholamines by digital simulation of cyclic voltammograms
Author(s) -
Afkhami Abbas,
Nematollahi Davood,
Khalafi Lida,
Rafiee Mohammad
Publication year - 2005
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20046
Subject(s) - chemistry , cyclic voltammetry , electrochemistry , reaction rate constant , dopamine , dissociation constant , intramolecular force , dissociation (chemistry) , medicinal chemistry , stereochemistry , kinetics , electrode , receptor , biochemistry , physics , quantum mechanics , neuroscience , biology
Electrochemical oxidation of some catecholamines such as dopamine ( 1 ), L ‐dopa ( 2 ), and methyldopa ( 3 ) has been studied in various pH values, using cyclic voltammetry. The results indicate participation of catecholamines ( 1–3 ) in intramolecular cyclization reaction to form the corresponding o ‐quinone derivatives ( 1d–3d ). In various pHs, based on ECE mechanism, the observed homogeneous rate constants ( k obs ) of cyclization reaction were estimated by comparing the experimental cyclic voltammetric responses with the digital‐simulated results. Also, the cyclization rate constants ( k cyc ) were calculated using microscopic acidic dissociation constant of ammonium groups. The significant differences in electrochemical behavior, k obs and k cyc , of L ‐dopa ( 2 ) and methyldopa ( 3 ) with dopamine ( 1 ) are due to the effects of the side chain carboxyl group. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 37: 17–24, 2005