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Kinetics of the homogeneous, unimolecular elimination reactions of ethyl oxamate, ethyl N,N ‐dimethyloxamate and ethyl oxanilate in the gas phase
Author(s) -
Chacin Esker V.,
Tosta María,
Herize Armando,
Domínguez Rosa M.,
Alvarado Ysaias,
Chuchani Gabriel
Publication year - 2005
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.894
Subject(s) - chemistry , arrhenius equation , bromide , torr , kinetics , atmospheric temperature range , reaction rate constant , allyl bromide , homogeneous , kinetic energy , partial pressure , phase (matter) , gas phase , thermodynamics , medicinal chemistry , analytical chemistry (journal) , activation energy , organic chemistry , oxygen , physics , quantum mechanics
The gas‐phase elimination kinetics of the title compounds were determined over the temperature range 350–430°C and pressure range 35–240 Torr (1 Torr = 133.3 Pa). The reactions, which were carried out in a static reactor system, seasoned with allyl bromide and in the presence of a free radical inhibitor, are homogeneous, unimolecular and obey a first‐order rate law. The temperature dependences of the overall rate coefficients are given by the following Arrhenius equations: for ethyl oxamate, log [ k 1 (s −1 )] = (13.28 ± 0.20) – (203.7 ± 2.5) kJ mol −1 (2.303 RT ) −1 , for ethyl N , N ‐dimethyloxamate, log [ k 1 (s −1 )] = (13.06 ± 0.34) – (206.8 ± 4.4) kJ mol −1 (2.303 RT ) −1 , and for ethyl oxanilate, log [ k 1 (s −1 )]= (13.86 ± 0.12)–(207.4 ± 1.5) kJ mol −1 (2.303 RT ) −1 . The overall rates, the partial rates and the kinetic and thermodynamic parameters of these eliminations are presented and discussed. These reactions appear to proceed through moderately polar cyclic transition states. Copyright © 2004 John Wiley & Sons, Ltd.