Kinetics of Hydrogen Abstraction and Addition Reactions of 3-Hexene by OH Radicals
Kinetics of Hydrogen Abstraction and Addition Reactions of 3-Hexene by OH Radicals
复制标题
OH 自由基对 3-己烯的夺氢和加成反应动力学
DOI：
10.1021/acsoica.6b11499
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发表时间：
2017
影响因子：
2.9
通讯作者：
Huang ZH
中科院分区：
文献类型：
--
作者：
Yang Feiyu;Deng Fuquan;Pan Youshun;Zhang Yingjia;Tang Chenglong;Huang Zuohua;Zhang YJ;Huang ZH
在CCSD（T）/CBS//BHandHLYP/6- 311 G（d，p）水平下计算了3-己烯与羟基自由基的吸氢和加成反应的势能面，并采用一维Wigner方法和正则变分过渡态方法修正了量子力学效应，多维零曲率隧道法和小曲率隧道法。结果表明，约70%的总H原子的提取发生在烯丙基位通过直接和间接渠道。含有两个货车德瓦耳斯预反应复合物的间接通道具有比直接通道大两倍的速率系数。OH加成反应也包含两个货车德瓦耳斯络合物，其浸没势垒导致在低温下的负温度系数行为。相比之下，OH加成反应仅在450 K以下占主导地位，而H原子夺取反应在1000 K以上占压倒性优势。所有的速率系数计算的不确定性的一个因素为5拟合在一个准阿克里乌斯公式。并对PES、最小反应路径和活化自由能进行了分析。
Rate coefficients of H atom abstraction and H atom addition reactions of 3-hexene by the hydroxyl radicals were determined using both conventional transition-state theory and canonical variational transition-state theory, with the potential energy surface (PES) evaluated at the CCSD(T)/CBS//BHandHLYP/6-311G(d,p) level and quantum mechanical effect corrected by the compounded methods including one-dimensional Wigner method, multidimensional zero-curvature tunneling method, and small-curvature tunneling method. Results reveal that accounting for approximate 70% of the overall H atom abstractions occur in the allylic site via both direct and indirect channels. The indirect channel containing two van der Waals prereactive complexes exhibits two times larger rate coefficient relative to the direct one. The OH addition reaction also contains two van der Waals complexes, and its submerged barrier results in a negative temperature coefficient behavior at low temperatures. In contrast, The OH addition pathway dominates only at temperatures below 450 K whereas the H atom abstraction reactions dominate overwhelmingly at temperature over 1000 K. All of the rate coefficients calculated with an uncertainty of a factor of 5 were fitted in a quasi-Arrhenius formula. Analyses on the PES, minimum reaction path and activation free Gibbs energy were also performed inthis study.