Jump to main content
Jump to site search

Issue 26, 2010
Previous Article Next Article

An ab initio/Rice-Ramsperger-Kassel-Marcus study of the hydrogen-abstraction reactions of methyl ethers, H3COCH3−x(CH3)x, x = 0–2, by ˙OH; mechanism and kinetics

Author affiliations

Abstract

A theoretical study of the mechanism and kinetics of the H-abstraction reaction from dimethyl (DME), ethylmethyl (EME) and iso-propylmethyl (IPME) ethers by the ˙OH radical has been carried out using the high-level methods CCSD(T)/CBS, G3 and G3MP2BH&H. The computationally less-expensive methods of G3 and G3MP2BH&H yield results for DME within 0.2–0.6 and 0.7–0.9 kcal mol−1, respectively, of the coupled cluster, CCSD(T), values extrapolated to the basis set limit. So the G3 and G3MP2BH&H methods can be confidently used for the reactions of the higher ethers. A distinction is made between the two different kinds of H-atoms, classified as in/out-of the symmetry plane, and it is found that abstraction from the out-of-plane H-atoms proceeds through a stepwise mechanism involving the formation of a reactant complex in the entrance channel and product complex in the exit channel. The in-plane H-atom abstractions take place through a more direct mechanism and are less competitive. Rate constants of the three reactions have been calculated in the temperature range of 500–3000 K using the Variflex code, based on the weak collision, master equation/microcanonical variational RRKM theory including tunneling corrections. The computed total rate constants (cm3 mol−1 s−1) have been fitted as follows: k(DME) = 2.74 × T3.94 exp (1534.2/T), k(EME) = 20.93 × T3.61 exp (2060.1/T) and k(IPME) = 0.55 × T3.93 exp (2826.1/T). Expressions of the group rate constants for the three different carbon sites are also provided.

Graphical abstract: An ab initio/Rice-Ramsperger-Kassel-Marcus study of the hydrogen-abstraction reactions of methyl ethers, H3COCH3−x(CH3)x, x = 0–2, by ˙OH; mechanism and kinetics

Back to tab navigation

Supplementary files

Publication details

The article was received on 10 Feb 2010, accepted on 22 Mar 2010 and first published on 19 May 2010


Article type: Paper
DOI: 10.1039/C002911D
Citation: Phys. Chem. Chem. Phys., 2010,12, 7221-7233
  •   Request permissions

    An ab initio/Rice-Ramsperger-Kassel-Marcus study of the hydrogen-abstraction reactions of methyl ethers, H3COCH3−x(CH3)x, x = 0–2, by ˙OH; mechanism and kinetics

    C. Zhou, J. M. Simmie and H. J. Curran, Phys. Chem. Chem. Phys., 2010, 12, 7221
    DOI: 10.1039/C002911D

Search articles by author

Spotlight

Advertisements