Is hydrogen abstraction an important pathway in the reaction of alkenes with the OH radical?

Abstract

In this paper, we report the first temperature dependent kinetic measurements of the reaction of C_≥5 1-alkenes with OH radicals and also report the first room temperature measurements for 1-alkenes between C₈₋₁₁. The rate coefficients at room temperature and between 75 and 100 Torr for the reaction of OH with 1-pentene, 1-octene, 1-nonene, 1-decene and 1-undecene are (2.74 ± 0.38) × 10⁻¹¹, (3.62 ± 0.68) × 10⁻¹¹, (4.20 ± 0.41) × 10⁻¹¹, (7.00 ± 0.96) × 10⁻¹¹ and (12.44 ± 1.62) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹, respectively, at 298 K. No pressure dependence is observed, suggesting that these reactions are at their high pressure limit. Inspection of the variation of rate coefficient with temperature over the temperature range 262–300 K shows a weak negative temperature dependence, suggesting that adduct formation is taking place, however, a curved Arrhenius plot is clearly seen for 1-decene and theoretical analysis suggests that abstraction by OH is a non-negligible channel. An estimation of products formed from OH oxidation suggests that abstraction will lead to products that have a lower photochemical ozone creation potential than those formed via addition.