Mechanism of the C{sub 2}H{sub 5}+O{sub 2} reaction

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.474610· OSTI ID:530060

Ignatyev, I S; Xie, Y; Allen, W D; Schaefer, III, H F ^[1]

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1. Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)

The geometries, energies, and vibrational frequencies of the reactants, transition states, intermediates, and products of the reaction of ethyl radical with the oxygen molecule have been examined using density functional theory (DFT). Rather different theoretical predictions are obtained from the BLYP, B3LYP, and BHLYP methods. Comparisons with experimental deductions and high-level coupled cluster results suggest that the B3LYP method is superior for the C{sub 2}H{sub 5}+O{sub 2} problem. Using the B3LYP method with a triple-zeta plus double-polarization plus f function (TZ2Pf) basis set, a transition state between the ethylperoxy radical and products is discovered which lies 3.3kcalmol{sup {minus}1} {ital below} reactants. This transition-state energy is consistent with the observed high yields of ethylene in the high-temperature reaction and is in good agreement with the height of the barrier estimated via modeling of the experimental kinetic data. However, this transition state (TS1) corresponds not to the internal proton transfer leading to the hydroperoxyethyl radical C{sub 2}H{sub 4}OOH but to the concerted elimination of ethylene. For the reverse reaction C{sub 2}H{sub 4}+HO{sub 2}{r_arrow}C{sub 2}H{sub 4}OOH, the TZ2Pf UB3LYP classical barrier is 11.2kcalmol{sup {minus}1}. {copyright} {ital 1997 American Institute of Physics.}

• DOE Contract Number: FG05-94ER14428
• OSTI ID: 530060
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 1 Vol. 107; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ALKANES
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COMBUSTION PRODUCTS
ETHYL RADICALS
ETHYLENE
ORGANIC COMPOUNDS
OXIDATION
OXYGEN
VIBRATIONAL STATES