Shang Y L, Shi J C, Fang L M, Feng Q G, Wang H Y, Luo S N
The Peac Institute of Multiscale Sciences , Chengdu , Sichuan 610031 , P. R. China.
J Phys Chem A. 2018 Aug 30;122(34):6829-6841. doi: 10.1021/acs.jpca.8b04943. Epub 2018 Aug 17.
Hydrogen abstractions by NO from symmetric ethers are investigated to determine the rate constants and explore the effect of the functional group on rate constants at different reaction sites. The involved ethers are dimethyl ether (DME), diethyl ether (DEE), dipropyl ether (DPE), and dibutyl ether (DBE). The B3LYP method with a 6-31G(2df,p) basis set is employed to optimize the ground-state geometries and for frequency and intrinsic reaction coordinate calculations. The G4 method is used to calculate the electronic energies for the small ethers (DME and DEE). Given the heavy computational cost of the G4 method, the modified G4MP2 method is applied for larger ethers (DPE and DBE) and also for DME to verify the accuracy of the G4MP2 method by benchmarking with the G4 method. The high-pressure limit rate constants are calculated within the temperature range of 500-2000 K, with the asymmetrical Eckart tunneling correction as well as one-dimensional hindered rotor treatment. The calculated rate constants agree well with the literature data, and the branch ratio analysis suggests that the cis-HONO channel basically dominates the hydrogen abstraction reactions and shows a decrease at high temperatures, followed by HNO and trans-HONO channels; in addition, the hydrogen abstraction at the C site adjacent to the ether bond (α reaction site) accounts for most of the reactions. Furthermore, the total rate constants of the ethers are compared to those of their half-structurally alkanes, and linear Bell-Evans-Polanyi correlations are observed.
研究了一氧化氮（NO）从对称醚类中夺取氢的反应，以确定速率常数，并探讨官能团对不同反应位点速率常数的影响。所涉及的醚类有二甲醚（DME）、二乙醚（DEE）、二丙醚（DPE）和二丁醚（DBE）。采用B3LYP方法和6-31G(2df,p)基组来优化基态几何结构，并进行频率和内禀反应坐标计算。G4方法用于计算小分子醚（DME和DEE）的电子能量。鉴于G4方法计算成本较高，对于较大的醚（DPE和DBE）以及DME，应用改进的G4MP2方法，并通过与G4方法对比来验证G4MP2方法的准确性。在500 - 2000 K的温度范围内，采用不对称埃卡特隧穿校正以及一维受阻转子处理来计算高压极限速率常数。计算得到的速率常数与文献数据吻合良好，分支比分析表明顺式-HONO通道基本主导了氢夺取反应，且在高温下有所下降，其次是HNO和反式-HONO通道；此外，在与醚键相邻的C位点（α反应位点）的氢夺取反应占大多数。此外，还将醚类的总速率常数与其半结构烷烃的总速率常数进行了比较，观察到了线性的贝尔-埃文斯-波拉尼相关性。
