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Stopped‐flow determination of carbon dioxide–diethanolamine reaction mechanism: Kinetics of carbamate formation
Author(s) -
Barth D.,
Tondre C.,
Delpuech J. J.
Publication year - 1983
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.550151104
Subject(s) - diethanolamine , chemistry , carbamate , reaction rate constant , kinetics , carbon dioxide , reaction mechanism , thermodynamics , order of reaction , reaction rate , inorganic chemistry , catalysis , organic chemistry , physics , quantum mechanics
The reaction mechanism of carbon dioxide with diethanolamine (DEA) is investigated using the stopped‐flow method with optical detection in the ranges of concentration [DEA] = 0.111–8.4 × 10 −2 M and [CO 2 ] = 2.94–5.6 × 10 −3 M . The comparison of the fast time‐dependent light transmission change of a pH indicator with theoretical simulations of integrated rate equations requires a kinetic model in which a simple carbamate formation takes place simultaneously with hydration reactions, whose contributions are far from being negligible. A first‐order reaction relative to DEA is thus found with a rate constant for carbamate formation smaller than usually predicted (110 ± 15 M −1 s −1 at 25°C). The equilibrium constant for the same reaction is also determined giving p K R = 5.3 at 25°C, in satisfactory agreement with values assumed so far.