Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

Kinetics of Homolytic Substitutions by Hydrogen Atoms at Thiols and Sulfides

Kinetics of Homolytic Substitutions by Hydrogen Atoms at Thiols and Sulfides Thermodynamic and kinetic data in the temperature range 300–1500 K are calculated for 94 homolytic substitution reactions by a hydrogen atom at thiols and sulfides with the CBS‐QB3//BMK/6‐311G(2d,d,p) method. The studied reactions were found to proceed according to a one‐step mechanism. A group additivity (GA) method is presented to model the Arrhenius parameters of this reaction family. The required GA values were derived from data obtained for a set containing 58 reactions. By using the developed GA scheme, rate coefficients at 300 K for 26 substitution reactions by the hydrogen atom are reproduced within a factor of 2.2. Mean absolute deviations on the activation energy and pre‐exponential factor are limited to 1.1 kJ mol−1 and 0.19, respectively. Rate coefficients for the reverse reactions, that is, substitution reactions by C‐ and S‐centered radicals with expulsion of a hydrogen atom, are reproduced within a factor of 6 by using thermodynamic consistency. At 1000 K, group additive and calculated rate coefficients for the forward and reverse reactions agree within a factor of 1.8 and 4, respectively. Experimental rate coefficients in the temperature range 300–400 K are reproduced within a factor of 5. Discrepancies between calculated and experimental data are discussed. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png ChemPhysChem Wiley

Kinetics of Homolytic Substitutions by Hydrogen Atoms at Thiols and Sulfides

Loading next page...
 
/lp/wiley/kinetics-of-homolytic-substitutions-by-hydrogen-atoms-at-thiols-and-LDIsnlGZkj

References (65)

Publisher
Wiley
Copyright
Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
ISSN
1439-4235
eISSN
1439-7641
DOI
10.1002/cphc.201201049
pmid
23589441
Publisher site
See Article on Publisher Site

Abstract

Thermodynamic and kinetic data in the temperature range 300–1500 K are calculated for 94 homolytic substitution reactions by a hydrogen atom at thiols and sulfides with the CBS‐QB3//BMK/6‐311G(2d,d,p) method. The studied reactions were found to proceed according to a one‐step mechanism. A group additivity (GA) method is presented to model the Arrhenius parameters of this reaction family. The required GA values were derived from data obtained for a set containing 58 reactions. By using the developed GA scheme, rate coefficients at 300 K for 26 substitution reactions by the hydrogen atom are reproduced within a factor of 2.2. Mean absolute deviations on the activation energy and pre‐exponential factor are limited to 1.1 kJ mol−1 and 0.19, respectively. Rate coefficients for the reverse reactions, that is, substitution reactions by C‐ and S‐centered radicals with expulsion of a hydrogen atom, are reproduced within a factor of 6 by using thermodynamic consistency. At 1000 K, group additive and calculated rate coefficients for the forward and reverse reactions agree within a factor of 1.8 and 4, respectively. Experimental rate coefficients in the temperature range 300–400 K are reproduced within a factor of 5. Discrepancies between calculated and experimental data are discussed.

Journal

ChemPhysChemWiley

Published: Jun 3, 2013

There are no references for this article.