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# Kinetic modeling of α-hydrogen abstractions from unsaturated and saturated oxygenate compounds by carbon-centered radicals

Paschalis Paraskevas (UGent) , Maarten Sabbe (UGent) , Marie-Françoise Reyniers (UGent) and Guy Marin (UGent)
(2014) 15(9). p.1849-1866
Author
Organization
Abstract
Hydrogen abstractions are important elementary reactions in a variety of reacting media at high temperatures in which oxygenates and hydrocarbon radicals are present. Accurate kinetic data are obtained from CBS-QB3 ab initio (AI) calculations by using conventional transition-state theory within the high-pressure limit, including corrections for hindered rotation and tunneling. From the obtained results, a group-additive (GA) model is developed that allows the Arrhenius parameters and rate coefficients for abstraction of the a-hydrogen from a wide range of oxygenate compounds to be predicted at temperatures ranging from 300 to 1500 K. From a training set of 60 hydrogen abstractions from oxygenates by carbon-centered radicals, 15 GA values (Delta GAV degrees s) are obtained for both the forward and reverse reactions. Among them, four Delta GAV degrees s refer to primary contributions, and the remaining 11 Delta GAV degrees s refer to secondary ones. The accuracy of the model is further improved by introducing seven corrections for cross-resonance stabilization of the transition state from an additional set of 43 reactions. The determined Delta AV degrees s are validated upon a test set of AI data for 17 reactions. The mean absolute deviation of the pre-exponential factors (log A) and activation energies (Ea) for the forward reaction at 300 K are 0.238 log(m(3) mol(-1) s(-1)) and 1.5 kJ mol(-1), respectively, whereas the mean factor of deviation <rho > between the GA-predicted and the AI-calculated rate coefficients is 1.6. In comparison with a compilation of 33 experimental rate coefficients, the <rho > between the GA-predicted values and these experimental values is only 2.2. Hence, the constructed GA model can be reliably used in the prediction of the kinetics of a-hydrogen-abstraction reactions between a broad range of oxygenates and oxygenate radicals.
Keywords
GROUP ADDITIVE VALUES, PHASE STANDARD ENTHALPY, HYDROCARBON RADICALS, BETA-SCISSION REACTIONS, TRANSITION-STATE-THEORY, group additivity, hydrogen abstraction, kinetic modeling, oxygen, ab initio calculations, REACTION-RATE PREDICTION, DIMETHYL ETHER, AB-INITIO, METHYL RADICALS, ACTIVATION-ENERGIES

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## Citation

Chicago
Paraskevas, Paschalis, Maarten Sabbe, Marie-Françoise Reyniers, Nikos Papayannakos, and Guy Marin. 2014. “Kinetic Modeling of Α-hydrogen Abstractions from Unsaturated and Saturated Oxygenate Compounds by Carbon-centered Radicals.” Chemphyschem 15 (9): 1849–1866.
APA
Paraskevas, P., Sabbe, M., Reyniers, M.-F., Papayannakos, N., & Marin, G. (2014). Kinetic modeling of α-hydrogen abstractions from unsaturated and saturated oxygenate compounds by carbon-centered radicals. CHEMPHYSCHEM, 15(9), 1849–1866.
Vancouver
1.
Paraskevas P, Sabbe M, Reyniers M-F, Papayannakos N, Marin G. Kinetic modeling of α-hydrogen abstractions from unsaturated and saturated oxygenate compounds by carbon-centered radicals. CHEMPHYSCHEM. 2014;15(9):1849–66.
MLA
Paraskevas, Paschalis, Maarten Sabbe, Marie-Françoise Reyniers, et al. “Kinetic Modeling of Α-hydrogen Abstractions from Unsaturated and Saturated Oxygenate Compounds by Carbon-centered Radicals.” CHEMPHYSCHEM 15.9 (2014): 1849–1866. Print.
@article{5674724,
abstract     = {Hydrogen abstractions are important elementary reactions in a variety of reacting media at high temperatures in which oxygenates and hydrocarbon radicals are present. Accurate kinetic data are obtained from CBS-QB3 ab initio (AI) calculations by using conventional transition-state theory within the high-pressure limit, including corrections for hindered rotation and tunneling. From the obtained results, a group-additive (GA) model is developed that allows the Arrhenius parameters and rate coefficients for abstraction of the a-hydrogen from a wide range of oxygenate compounds to be predicted at temperatures ranging from 300 to 1500 K. From a training set of 60 hydrogen abstractions from oxygenates by carbon-centered radicals, 15 GA values (Delta GAV degrees s) are obtained for both the forward and reverse reactions. Among them, four Delta GAV degrees s refer to primary contributions, and the remaining 11 Delta GAV degrees s refer to secondary ones. The accuracy of the model is further improved by introducing seven corrections for cross-resonance stabilization of the transition state from an additional set of 43 reactions. The determined Delta AV degrees s are validated upon a test set of AI data for 17 reactions. The mean absolute deviation of the pre-exponential factors (log A) and activation energies (Ea) for the forward reaction at 300 K are 0.238 log(m(3) mol(-1) s(-1)) and 1.5 kJ mol(-1), respectively, whereas the mean factor of deviation {\textlangle}rho {\textrangle} between the GA-predicted and the AI-calculated rate coefficients is 1.6. In comparison with a compilation of 33 experimental rate coefficients, the {\textlangle}rho {\textrangle} between the GA-predicted values and these experimental values is only 2.2. Hence, the constructed GA model can be reliably used in the prediction of the kinetics of a-hydrogen-abstraction reactions between a broad range of oxygenates and oxygenate radicals.},
author       = {Paraskevas, Paschalis and Sabbe, Maarten and Reyniers, Marie-Fran\c{c}oise and Papayannakos, Nikos and Marin, Guy},
issn         = {1439-4235},
journal      = {CHEMPHYSCHEM},
language     = {eng},
number       = {9},
pages        = {1849--1866},
title        = {Kinetic modeling of \ensuremath{\alpha}-hydrogen abstractions from unsaturated and saturated oxygenate compounds by carbon-centered radicals},
url          = {http://dx.doi.org/10.1002/cphc.201400039},
volume       = {15},
year         = {2014},
}


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