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Steric factors in the gas phase elimination kinetics of ethyl N ‐benzyl‐ N ‐cyclopropylcarbamate and ethyl diphenylcarbamate
Author(s) -
Luiggi Marniev,
Dominguez Rosa M.,
Rotinov Alexandra,
Herize Armando,
Cordova Mary,
Chuchani Gabriel
Publication year - 2002
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.10010
Subject(s) - chemistry , steric effects , arrhenius equation , medicinal chemistry , atmospheric temperature range , amine gas treating , kinetics , decomposition , reaction rate constant , carbon monoxide , organic chemistry , activation energy , catalysis , thermodynamics , physics , quantum mechanics
The elimination kinetics of ethyl N ‐benzyl‐ N ‐cyclopropylcarbamate and ethyl diphenylcarbamate were investigated over the temperature range of 349.9–440.0°C and the pressure range of 31–106 Torr. These reactions have been found to be homogeneous, unimolecular, and obey a first‐order rate law. The products are ethylene, carbon monoxide, and the corresponding secondary amine. The rate coefficient is expressed by the following Arrhenius equations: For ethyl N ‐benzyl‐ N ‐cyclopropylcarbamate log k 1 (s −1 ) = (12.94 ± 0.09) − (198.5 ± 0.9) kJ mol −1 (2.303RT) −1For ethyl diphenylcarbamate log k 1 (s −1 ) = (12.91 ± 0.18) − (208.2 ± 2.4) kJ mol −1 (2.303RT) −1The presence of phenyl and bulky groups at the nitrogen atom of the ethylcarbamate showed a decrease in the rate of elimination. Steric factor may be operating during the process of decomposition of these substrates. These reactions appear to undergo a semipolar six‐membered cyclic transition type of mechanism.© 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 67–71, 2002