Comparative kinetics of the 3-buten-1-ol and 1-butene reactions with OH radicals: a density functional theory/RRKM investigation

SILVINA PEIRONE, JORGE D. NIETO, PABLO M. COMETTO, THAÍS DA SILVA BARBOSA, GALUCO FAVILLA BAUERFELDT, GRACIELA ARBILLA AND SILVIA I. LANE

JOURNAL OF PHYSICAL CHEMISTRY A

AMER CHEMICAL SOC

Lugar: Washington; Año: 2015 vol. 119 p. 3171 - 3180

1089-5639

ABSTRACT: The compared kinetics of the reactions ofunsaturated alcohols and alkenes with OH radicals is a topic ofgreat interest from both the theoretical chemistry and theatmospheric chemistry points of view. The enhanced reactivityof an unsaturated alcohol, with respect to its alkene analogue,toward OH radicals has been previously demonstrated, at 298 K,by experimental and theoretical research. In this work, a newcomparative investigation of such reactions is performed for 3-buten-1-ol and 1-butene. The model assumes that the overallkinetics is governed by the first OH addition steps of themechanism. Calculations have been performed at the DFT level,employing the BHandHLYP functional and the cc-pVDZ and augcc-pVDZ basis sets, and the rate coefficients have been determinedon the basis of the microcanonical variational transition state theory. The rate coefficients obtained for the OH reactions with 3-buten-1-ol (kOH31BO) and 1-butene (kOH1B) at 298.15 K are lower than the experimental rate coefficient available in the literature,showing deviations of 18% and 25%, respectively. Negative temperature dependence is verified for these rate coefficients. ThekOH31BO/kOH1B ratios have also been investigated as a function of the temperature, suggesting that at room temperature theunsaturated alcohol reacts with the OH radicals faster than 1-butene, by a factor of 1.2, but at higher temperatures (400−500 K),the alkene should react faster, and that the stabilization of prebarrier complexes and saddle points due to hydrogen bonds is nolonger an important factor to govern the reactivity of the unsaturated alcohol toward OH radicals, with respect to the alkeneanalogue.