Experimental and theoretical studies of the kinetics of the OH + hydroxyacetone reaction as a function of temperature.

The rate constant for the reaction of the OH radical with hydroxyacetone was measured between 2 and 5 Torr and over the temperature range of 280-350 K, using a discharge-flow system coupled with resonance fluorescence detection of the OH radical. At 298 K the rate constant was found to be (3.02 +/- 0.28) x 10(-12) cm3 molecule(-1) s(-1), in excellent agreement with several previous studies. A positive temperature dependence was measured over the temperature range 280-350 K, described by the Arrhenius expression k = (1.88 +/- 0.75) x 10(-11) exp[-(545 +/- 60)/T] cm3 molecule(-1) s(-1), in contrast to previous measurements of the temperature dependence for this reaction and suggesting that the atmospheric lifetime of hydroxyacetone may be greater than previously estimated. Theoretical calculations of the potential energy surface for this reaction suggest that the mechanism for this reaction involves hydrogen abstraction through a hydrogen-bonded prereactive complex similar to the OH + acetone reaction, with a calculated barrier height between -1 and 1 kcal mol(-1) depending on the level of theory.