High-level electronic structure calculations and master equation analyses were carried out to obtain the pressure- and temperature-dependent rate constants of the methyl vinyl ketone + OH and methacrolein + OH reactions. The balance between the OH addition reactions at the high-pressure limit, the OH addition reactions in the fall-off region, and the pressure-independent hydrogen abstractions involved in these multiwell and multi-channel systems, has been shown to be crucial to understand the pressure and temperature dependence of each global reaction. In particular, the fall-off region of the OH addition reactions contributes to the inverse temperature dependence of the rate constants in the Arrhenius plots, leading to pressure-dependent negative activation energies. The pressure dependence of the methyl vinyl ketone + OH reaction is clearly more important than in the case of the methacrolein + OH reaction owing to the weight of the hydrogen abstraction process in this second system. Comparison of the theoretical rate constants and the experimental measurements shows quite good agreement. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.
|Journal||Chemistry - A European Journal|
|Publication status||Published - 5 Feb 2007|
- Gas-phase reactions
- Master equation
- Methyl vinyl ketone