Rate constants for the gas-phase reactions of OH radicals with E-7-tetradecene, 2-methyl-1-tridecene and the C7–C14 1-alkenes at 295 ± 1 K

Abstract

Rate constants for the gas-phase reactions of OH radicals with the C₇–C₁₄ 1-alkenes and with E-7-tetradecene and 2-methyl-1-tridecene have been measured at 295 ± 1 K and atmospheric pressure of air using a relative rate technique. The rate constants obtained (in units of 10⁻¹¹ cm³ molecule⁻¹ s⁻¹) were: 1-heptene, 3.86 ± 0.12; 1-octene, 4.14 ± 0.08; 1-nonene, 4.32 ± 0.05; 1-decene, 4.61 ± 0.14; 1-undecene, 4.79 ± 0.11; 1-dodecene, 5.03 ± 0.13; 1-tridecene, 5.09 ± 0.17; 1-tetradecene, 4.96 ± 0.28; E-7-tetradecene, 7.47 ± 0.53; and 2-methyl-1-tridecene, 8.69 ± 0.27, where the indicated errors are two least-squares standard deviations and do not include the uncertainty associated with the rate constant for the reference compound α-pinene. While our rate constants for 1-octene and 1-nonene agree with those at 298 K recently measured using an absolute rate method, our rate constants for 1-decene and 1-undecene are lower by factors of 1.5 and 2.6, respectively. Combined with previous rate constants from this laboratory for the C₄–C₇ 1-alkenes, our data show that the rate constants for the reactions of OH radicals with 1-alkenes increase linearly with increasing carbon number, with the increase per additional CH₂ group being a factor of ∼1.4–1.5 higher than that observed in the n-alkane series. The rate constants measured for E-7-tetradecene and 2-methyl-1-tridecene suggest that the increase in rate constant per additional CH₂ group ranges from being similar to that in the n-alkanes series to being a factor of ∼2 higher.