Kinetics of the hydrogen atom abstraction reactions from 1-butanol by hydroxyl radical: theory matches experiment and more.
Kinetics of the hydrogen atom abstraction reactions from 1-butanol by hydroxyl radical: theory matches experiment and more.
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DOI：
10.1021/jp310910f
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发表时间：
2013-01
期刊：
影响因子：
--
通讯作者：
P. Seal;Gbenga A. Oyedepo;D. Truhlar
中科院分区：
文献类型：
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作者：
P. Seal;Gbenga A. Oyedepo;D. Truhlar
本文研究了羟基自由基在正丁醇分子五个位置上的夺氢反应。采用多结构变分过渡态理论（MS-VTST）估算了5个热反应速率常数。MS-VTST利用了一个多方面的划分表面，占过渡态的多个构象结构，我们还包括所有的反应物分子的结构。使用M08-HX/MG 3S电子结构方法计算振动频率和最小能量路径（MEP）。所需的势能面得到隐式的直接动力学采用插值变分过渡态理论与映射（IVTST-M），使用变分反应路径算法。然后使用M08-HX/MG 3S电子模型化学计算多结构扭转非谐因子，以完成MS-VTST速率常数计算。结果表明，扭转非谐性在较高温度下是非常重要的，忽略它将导致在1000和1500 K的误差分别为26和32。在896-1269 K时，我们的结果与Hanson及其同事的实验值以及坎贝尔等人在292 K时的实验值吻合得很好，但与Wallington等人的实验值稍差。纳尔逊等人，和Yujing和Mellouki在253-372 K;然而，计算的速率在所有温度下的所有实验值的1.61倍之内。这使我们对特定地点的值有信心，目前无法进行实验。
In the present work, we study the H atom abstraction reactions by hydroxyl radical at all five sites of 1-butanol. Multistructural variational transition state theory (MS-VTST) was employed to estimate the five thermal rate constants. MS-VTST utilizes a multifaceted dividing surface that accounts for the multiple conformational structures of the transition state, and we also include all the structures of the reactant molecule. The vibrational frequencies and minimum energy paths (MEPs) were computed using the M08-HX/MG3S electronic structure method. The required potential energy surfaces were obtained implicitly by direct dynamics employing interpolated variational transition state theory with mapping (IVTST-M) using a variational reaction path algorithm. The M08-HX/MG3S electronic model chemistry was then used to calculate multistructural torsional anharmonicity factors to complete the MS-VTST rate constant calculations. The results indicate that torsional anharmonicity is very important at higher temperatures, and neglecting it would lead to errors of 26 and 32 at 1000 and 1500 K, respectively. Our results for the sums of the site-specific rate constants agree very well with the experimental values of Hanson and co-workers at 896-1269 K and with the experimental results of Campbell et al. at 292 K, but slightly less well with the experiments of Wallington et al., Nelson et al., and Yujing and Mellouki at 253-372 K; nevertheless, the calculated rates are within a factor of 1.61 of all experimental values at all temperatures. This gives us confidence in the site-specific values, which are currently inaccessible to experiment.