| Abstract
| - The product distribution of the reaction of acetic acid, CH3COOH, with hydroxyl radicals, OH, was studiedexperimentally and theoretically. Mass-spectrometric measurements at 290 K and 2 Torr of He of the CO2yield versus the loss of acetic acid yielded a branching fraction of 64 ± 14% for the abstraction of the acidichydrogen as follows: CH3COOH + OH → CH3COO + H2O → CH3 + CO2 + H2O. A quantum chemicaland theoretical kinetic analysis showed that the abstraction of the acidic hydrogen is enhanced relative to theabstraction of −CH3 hydrogens because of the formation of a strong pre-reactive H-bonded complex, wherethe H-bonds are retained in the H-abstraction transition state. The potential energy surface of the reaction isexplored in detail, and the reaction products of the individual channels are identified. The theoretical productbranching is found to be critically dependent on the energetic and rovibrational differences between theH-abstraction transition states.
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