Ab initio and RRKM calculations for multichannel rate constants of the C{sub 2}H{sub 3}+O{sub 2} reaction

Journal Article · Wed Oct 09 04:00:00 EDT 1996 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja961476e· OSTI ID:420864

Mebel, A M; Diau, E W.G.; Lin, M C; Morokuma, K ^[1]

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1. Emory Univ., Atlanta, GA (United States)

A potential energy surface for the reaction of vinyl radical with molecular oxygen has been studied using the ab initio G2M(RCC, MP2) method. The most favorable reaction pathway leading to the major CHO+CH{sub 2}O products is described. The C{sub 2}H{sub 3}O+O products can be formed by elimination of the oxygen atom from C{sub 2}H{sub 3}OO via TS 23, which is by 7.8 kcal/mol lower in energy than the reactants, but by 6.5 kcal/mol higher than TS 9`. The hydrogen migration in 1` gives rise to another significant product channel: C{sub 2}H{sub 3}+O{sub 2} {yields} 1` {yields} TS 25` {yields} C{sub 2}H{sub 2}+O{sub 2}H, with TS 25` lying below C{sub 2}H{sub 3}+O{sub 2} by 3.5 kcal/mol. Multichannel RRKM calculations have been carried out for the total and individual rate constants for various channels using the G2M(RCC, MP2) energetics and molecular parameters of the intermediates and transition states. The computed low pressure reaction rate constant is in quantitative agreement with experiment. At atmospheric pressure, the title reaction is dominated by the stabilization of vinylperoxy radical C{sub 2}H{sub 3}OO at room temperature. In the 500-900 K temperature range, the CHO+CH{sub 2}O channel has the highest rate constant, and at T >= 900 K, C{sub 2}H{sub 3}O+O are the major products. At very high temperatures, the channel producing C{sub 2}H{sub 2} + O{sub 2}H becomes competitive. 15 refs., 3 figs., 4 tabs.

• DOE Contract Number: FG05-91ER14191
• OSTI ID: 420864
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 40 Vol. 118; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
66 PHYSICS
99 GENERAL AND MISCELLANEOUS
CALCULATION METHODS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
MOLECULAR MODELS
MOLECULAR ORBITAL METHOD
OXYGEN
PRESSURE DEPENDENCE
TEMPERATURE RANGE
THEORETICAL DATA
VINYL RADICALS