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3238046 
Journal Article 
Kinetics and mechanism of the reactions of CH3CO and CH3C(O)CH2 radicals with O-2. Low-pressure discharge flow experiments and quantum chemical computations 
Kovacs, G; Zador, J; Farkas, E; Nadasdi, R; Szilagyi, I; Dobe, S; Berces, T; Marta, F; Lendvay, G 
2007 
1 
Physical Chemistry Chemical Physics
ISSN: 1463-9076
EISSN: 1463-9084 
9 
31 
4142-4154 
WOS:000249100500016 
The reactions CH3CO + O-2 -> products (1), CH3CO + O-2 -> OH
+other products (1b) and CH3C(O)CH2 + O-2 - products (2) have been studied in isothermal
discharge flow reactors with laser induced fluorescence monitoring of OH and CH3C(O)CH2 radicals.
The experiments have been performed at overall pressures between 1.33 and 10.91 mbar of helium
and 298 +/-1 K reaction temperature. OH formation has been found to be the dominant reaction
channel for CH3CO + O-2: the branching ratio, Gamma(1b) = k(1b)/k(1,) is close to unity at around
I mbar, but decreases rapidly with increasing pressure. The rate constant of the overall
reaction, k(2), has been found to be pressure dependent: the fall-off behaviour has been analysed
in comparison with reported data. Electronic structure calculations have confirmed that at room
temperature the reaction of CH3C(O)CH2 with O-2 is essentially a recombination- type process. At
high temperatures, the further reactions of the acetonyl-peroxyl adduct may yield OH radicals,
but the most probable channel seems to be the O-2-catalysed keto-enol transformation of acetonyl.
Implications of the results for atmospheric modelling studies have been discussed.