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Abnormally slow reaction of oppositely charged ions: The kinetics of dopamine hydrochloride oxidation by ammonium peroxydisulfate
Author(s) -
Mezhuev Yaroslav O.,
Varankin Alexander V.,
Luss Anna L.,
Dyatlov Valerie A.,
Tsatsakis Aristides M.,
Stratidakis Antonios K.,
Korshak Yuri V.
Publication year - 2020
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.21367
Subject(s) - chemistry , peroxydisulfate , activation energy , entropy of activation , aqueous solution , redox , inorganic chemistry , order of reaction , kinetics , ion , ammonium , reaction rate , hydrochloride , half reaction , reaction rate constant , catalysis , organic chemistry , physics , quantum mechanics
The kinetic curves for oxidation of dopamine hydrochloride in aqueous solution in the presence of ammonium peroxydisulfate were obtained by UV–vis spectroscopy and potentiometry. It was shown that the reaction follows the first‐order kinetic equation and proceeds at a low rate. The values for the activation energy and the preexponential factor were determined as 75 kJ × mol −1 and 4 × 10 8 s −1 , respectively. The activation entropy was found having a negative value of −89 J × mol −1 × K −1 . The first reaction order, the low preexponential factor and the negative activation entropy value for the reaction between the 2‐(3,4‐dihydroxyphenyl)ethanammonium cation and the peroxydisulfate anion were explained by the formation of ionic associates, which slowly enter into the internal redox reaction.