In this work, the kinetics of reaction class of hydrogen abstraction from saturated hydrocarbons by O2 molecules has been studied. The high-pressure reaction rate constants were determined using reaction class transition state theory/structure-activity relationship (RC-TST/SAR) methodology, augmented by linear energy relationship (LER) and/or barrier height grouping (BHG) approximations for evaluation of the reaction barrier heights. The parameters needed have been derived from DFT calculations at M06-2X/aug-cc-pVTZ level for a training set of 23 reactions, involving hydrogen abstraction by O2 molecule at primary, secondary, and tertiary carbon sites. The reference reaction rate constant C2H6 + O2 → C2H5 + HO2 was obtained by extrapolation of the simplest reaction within the title family CH4 + O2 → CH3 + HO2. Kinetic parameters of the later one, calculated from canonical variational transition state theory (CVT), were taken from literature. The influence of low-frequency internal rotations has been investigated in details. The error analysis shows that the average systematic error of RC-TST/SAR-derived rate constants at low temperatures is within 25% compared to the explicit RC-TST results and diminishes at higher temperatures. This suggests that the proposed methodology can be effectively implemented in the automated mechanism generation codes to create the fuel combustion mechanisms.

中文翻译：

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烷烃+O2→烷基+HO2反应类的夺氢动力学：反应类过渡态理论的应用

在这项工作中，研究了O2分子从饱和烃中夺氢的反应类动力学。高压反应速率常数是使用反应类过渡态理论/结构-活性关系 (RC-TST/SAR) 方法确定的，通过线性能量关系 (LER) 和/或势垒高度分组 (BHG) 近似值来增强，以评估反应势垒高度。所需的参数来自于 M06-2X/aug-cc-pVTZ 级别的 DFT 计算，用于训练集 23 个反应，涉及 O2 分子在一级、二级和三级碳位点的氢提取。参考反应速率常数 C2H6 + O2 → C2H5 + HO2 是通过对标题族 CH4 + O2 → CH3 + HO2 中最简单的反应进行外推获得的。后者的动力学参数，从规范变分过渡态理论（CVT）计算，取自文献。已经详细研究了低频内旋的影响。误差分析表明，与显式RC-TST结果相比，低温下RC-TST/SAR导出的速率常数的平均系统误差在25%以内，并在较高温度下减小。这表明所提出的方法可以有效地在自动机制生成代码中实施，以创建燃料燃烧机制。误差分析表明，与显式RC-TST结果相比，低温下RC-TST/SAR导出的速率常数的平均系统误差在25%以内，并在较高温度下减小。这表明所提出的方法可以有效地在自动机制生成代码中实施，以创建燃料燃烧机制。误差分析表明，与显式RC-TST结果相比，低温下RC-TST/SAR导出的速率常数的平均系统误差在25%以内，并在较高温度下减小。这表明所提出的方法可以有效地在自动机制生成代码中实施，以创建燃料燃烧机制。