Title
Effects of entropy on the gas-phase pyrolysis of ethyl N, N-dimethylcarbamate
Abstract
In this study, we examined the gas-phase pyrolysis of ethyl N,N-dimethylcarbamate theoretically at various theoretical levels. The reaction consists of a two-step mechanism, with N,N-dimethylcarbamic acid and ethylene as reaction intermediates. In the first step, the reaction proceeds via a six-membered cyclic transition state (TS), which is more favorable than that via a four-membered cyclic TS. Here, the contribution of entropy to the overall potential energy surface was found to play an important role in determining the rate-limiting step, which was found to be the second step when viewed in terms of the enthalpy of activation (Delta H-not equal), but the first step when entropy changes (-T Delta S-not equal) were considered. These results are consistent with experimental findings. Moreover, the experimental activation entropy can be reproduced by using the hindered rotor approximation, which converts some low vibration frequencies that correspond to internal rotational modes into hindered rotors. (C) 2006 Wiley Periodicals, Inc.
Year
DOI
Venue
2007
10.1002/jcc.20600
JOURNAL OF COMPUTATIONAL CHEMISTRY
Keywords
Field
DocType
pyrolysis of N,N-dimethylcarbamate,ab initio,cyclic transition states,entropy effect,hindered rotor approximation
Ethylene,Potential energy surface,Thermodynamics,Computational chemistry,Chemistry,Rotor (electric),Ab initio,Vibration,Pyrolysis,Reaction intermediate,Enthalpy
Journal
Volume
Issue
ISSN
28
3
0192-8651
Citations 
PageRank 
References 
0
0.34
0
Authors
6
Name
Order
Citations
PageRank
Chang Kon Kim122.75
Dong J. Kim200.34
Y. Hsieh300.34
Hai Whang Lee422.07
Bon-su Lee521.74
Chan Kyung Kim6207.00