Department of Chemistry , University of Helsinki , P.O. Box 55 (A.I. Virtasen aukio 1), FI-00014 , Helsinki , Finland.
School of Engineering , Brown University , Providence , Rhode Island 02912 , United States.
J Phys Chem A. 2019 Sep 19;123(37):7897-7910. doi: 10.1021/acs.jpca.9b03923. Epub 2019 Sep 10.
The kinetics and thermochemistry of the pent-1-en-3-yl radical reaction with molecular oxygen (CHCHCHCHCH + O) has been studied by both experimental and computational methods. The bimolecular rate coefficient of the reaction was measured as a function of temperature (198-370 K) and pressure (0.2-4.5 Torr) using laser photolysis-photoionization mass-spectrometry. Quantum chemical calculations were used to explore the potential energy surface of the reaction, after which Rice-Ramsperger-Kassel-Marcus theory/master equation simulations were performed to investigate the reaction. The experimental data were used to adjust key parameters, such as well depths, in the master equation model within methodological uncertainties. The master equation simulations suggest that the formation rates of the two potential RO adducts are equal and that the reaction to QOOH is slower than for saturated hydrocarbons. The initial addition reaction, CHCHCHCHCH + O, is found to be barrierless when accounting for multireference effects. This is in agreement with the current experimental data, as well as with past experimental data for the allyl + O reaction. Finally, we conducted numerical simulations of the pent-1-en-3-yl + O reaction system and observed significant amounts of penta-1,3-diene being formed under engine-relevant conditions.
通过实验和计算方法研究了戊-1-烯-3-基自由基与分子氧（CHCHCHCHCH + O）的反应动力学和热化学。使用激光光解-光离子化质谱法，在 198-370 K 和 0.2-4.5 Torr 的温度和压力下测量了反应的双分子速率系数。量子化学计算用于探索反应的势能面，之后进行 Rice-Ramsperger-Kassel-Marcus 理论/主方程模拟以研究反应。实验数据用于在方法不确定性内调整主方程模型中的关键参数，例如势阱深度。主方程模拟表明，两个潜在的 RO 加合物的形成速率相等，并且与饱和烃相比，反应到 QOOH 的速度较慢。当考虑多参考效应时，发现 CHCHCHCHCH + O 的初始加成反应是无势垒的。这与当前的实验数据以及过去的丙烯基+ O 反应的实验数据一致。最后，我们对戊-1-烯-3-基+ O 反应体系进行了数值模拟，并在与发动机相关的条件下观察到大量的戊-1,3-二烯形成。
