  In order to improve the understanding of the low temperature combustion of
ethanol, high-level ab initio calculations were performed for elementary
reactions involving hydroxyethylperoxy radicals. These radicals come from the
addition of hydroxethyl radicals (?CH3CHOH and ?CH2CH2OH) on oxygen molecule.
Unimolecular reactions involving hydroxyethylperoxy radicals and their radical
products were studied at the CBS-QB3 level of theory. The results allowed to
highlight the principal ways of decomposition of these radicals. Calculations
of potential energy surfaces showed that the principal channels lead to the
formation of HO2 radicals which can be considered, at low temperature, as
slightly reactive. However, in the case of CH3CH(OOH)O? radicals, a route of
decomposition yields H atom and formic peracid, which is a branching agent that
can strongly enhance the reactivity of ethanol in low temperature oxidation. In
addition to these analyses, high-pressure limit rate constants were derived in
the temperature range 400 to 1000 K.
