A comparison of primary and secondary hydrogen abstraction from organophosphates by hydroxyl radical

Douglas S. Burns, Marshall G. Cory, Decarlos E. Taylor, Steven W. Bunte, Keith A Runge, Joseph L. Vasey

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

To compare the effect of primary and secondary CH bonds on hydrogen atom abstraction by hydroxyl radical, rate constants for the reactions of OH radicals with trimethyl phosphate [TMPO, (CH3O) 3P(O)] and triethyl phosphate [TEPO, (CH3CH 2O)3P(O)] have been calculated using the semiclassical flux-flux autocorrelation function (SCFFAF) method and compared with experimental measurements over the temperature range 250-350 K. SCFFAF specifies that structures be obtained at the CCSD/6 31++G* level of chemical theory and the height of the activation barrier be determined using an energy extrapolation, here a variant of the G2MP2 method. Dynamics are generated in the SCFFAF method from forces computed with a transfer Hamiltonian, which provides information about the curvature of the potential energy surface in the neighborhood of the transition state (TS), as well as the required internal forces. The temperature dependent reaction rate constants are calculated for the various possible abstraction pathways, primary hydrogen atom abstraction in the case of TMPO, and primary and secondary in the case of TEPO. Since two energetically favorable parent structures for each system are included in the model, the activation energy is calculated with respect to the conformer that connects to a given TS and the total rate constant at a given temperature is Boltzmann weighted with respect to the parent conformer. The computed temperature dependent rate curves are consistent with published experimental data in both magnitude and temperature dependence. © 2013 Wiley Periodicals, Inc. Int J Chem Kinet 45: 187-201, 2013

Original languageEnglish (US)
Pages (from-to)187-201
Number of pages15
JournalInternational Journal of Chemical Kinetics
Volume45
Issue number3
DOIs
StatePublished - Mar 2013
Externally publishedYes

Fingerprint

Organophosphates
hydroxyl radicals
Hydroxyl Radical
Hydrogen
Fluxes
Temperature
hydrogen
Autocorrelation
autocorrelation
Rate constants
hydrogen atoms
phosphates
Hamiltonians
Atoms
Potential energy surfaces
temperature
Extrapolation
Reaction rates
extrapolation
reaction kinetics

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Biochemistry

Cite this

A comparison of primary and secondary hydrogen abstraction from organophosphates by hydroxyl radical. / Burns, Douglas S.; Cory, Marshall G.; Taylor, Decarlos E.; Bunte, Steven W.; Runge, Keith A; Vasey, Joseph L.

In: International Journal of Chemical Kinetics, Vol. 45, No. 3, 03.2013, p. 187-201.

Research output: Contribution to journalArticle

Burns, Douglas S. ; Cory, Marshall G. ; Taylor, Decarlos E. ; Bunte, Steven W. ; Runge, Keith A ; Vasey, Joseph L. / A comparison of primary and secondary hydrogen abstraction from organophosphates by hydroxyl radical. In: International Journal of Chemical Kinetics. 2013 ; Vol. 45, No. 3. pp. 187-201.
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