What is the origin of the contrathermodynamic behavior in methyl radical addition to alkynes versus alkenes?

Gomez-Balderas, R, Coote, M, Henry, D and Radom, L 2003, 'What is the origin of the contrathermodynamic behavior in methyl radical addition to alkynes versus alkenes?', Journal of Physical Chemistry Part A, vol. 107, no. 31, pp. 6082-6090.


Document type: Journal Article
Collection: Journal Articles

Title What is the origin of the contrathermodynamic behavior in methyl radical addition to alkynes versus alkenes?
Author(s) Gomez-Balderas, R
Coote, M
Henry, D
Radom, L
Year 2003
Journal name Journal of Physical Chemistry Part A
Volume number 107
Issue number 31
Start page 6082
End page 6090
Total pages 9
Publisher American Chemical Society
Abstract High-level ab initio calculations of the barriers, enthalpies, and rate constants have been performed for methyl radical addition to ethyne, propyne, ethene, and propene. We find that addition to alkenes is kinetically favored over addition to alkynes, despite the larger exothermicity of the alkyne addition reactions. The results have been rationalized using the curve-crossing model. To this end, the singlet-triplet gaps and charge-transfer energies in the reactants, and the extent of charge separation in the transition structures, have been calculated. It is concluded that the greater barrier for addition to alkynes is primarily the result of the larger singlet-triplet gap in the substrate. This barrier-raising effect dominates the barrier-lowering effect of the reaction exothermicity.
Subject Chemical Thermodynamics and Energetics
Reaction Kinetics and Dynamics
DOI - identifier 10.1021/jp035042z
Copyright notice © 2003 American Chemical Society
ISSN 1089-5639
Versions
Version Filter Type
Citation counts: Scopus Citation Count Cited 26 times in Scopus Article | Citations
Altmetric details:
Access Statistics: 170 Abstract Views  -  Detailed Statistics
Created: Thu, 16 Dec 2010, 10:43:00 EST by Catalyst Administrator
© 2014 RMIT Research Repository • Powered by Fez SoftwareContact us