Yang Jing, Li Qian Shu, Zhang Shaowen
Department of Chemistry, Tangshan Teacher's College, Tangshan 063000, People's Republic of China.
J Comput Chem. 2008 Jan 30;29(2):247-55. doi: 10.1002/jcc.20783.
The hydrogen abstraction reaction of ozone with acetaldehyde has been studied theoretically over the temperature range 250-2500 K. Two different reactive sites of acetaldehyde molecule, CH(3) and CHO groups have been investigated, and results confirm that the CHO group is a highly reactive site. In this study, the geometries and harmonic vibrational frequencies of all stationary points are calculated at the MPW1K, BHandHLYP, and MPWB1K levels of theory. The minimum energy paths (MEPs) were obtained at the MPW1K/6-31+G(d,p) level of theory. To refine the energies along the MEPs of each channel, single-point energy calculations were performed by a higher-level energy calculation method (denoted as HL). The rate constants were evaluated based on the MEPs from the HL method in the temperature range 250-2500 K by using the conventional transition state theory (TST), the canonical variational transition state theory (CVT), the microcanonical variational transition state theory (muVT), the CVT coupled with small-curvature tunneling (SCT) correction (CVT/SCT), and the muVT coupled with Eckart tunneling correction (muVT/Eckart). The fitted three-parameter Arrhenius expressions of the calculated CVT/SCT and muVT/Eckart rate constants of the H abstraction from CHO group are k CVT/SCT(T) = 4.92 x 10(-27).T 3.77.e(-7867.0/T) and k muVT/Eckart(T) = 2.10 x 10(-27).T(3.90).e(-7706.2/T), respectively. The fitted three-parameter Arrhenius expressions of the calculated CVT/SCT and muVT/Eckart rate constants of the H abstraction from CH3 group are k(CVT/SCT)(T) = 1.27 x 10(-27).T(3.94).e(-14554.1/T) and k muVT/Eckart(T) = 1.62 x 10(-26).T(3.66).e(-15459.8/T), respectively.
在250 - 2500 K的温度范围内，从理论上研究了臭氧与乙醛的氢提取反应。研究了乙醛分子的两个不同反应位点，即CH(3)和CHO基团，结果证实CHO基团是一个高反应性位点。在本研究中，所有驻点的几何结构和谐波振动频率在MPW1K、BHandHLYP和MPWB1K理论水平上进行了计算。最小能量路径（MEP）在MPW1K/6 - 31 + G(d,p)理论水平上获得。为了细化每个通道沿MEP的能量，采用更高水平的能量计算方法（记为HL）进行单点能量计算。在250 - 2500 K的温度范围内，基于HL方法的MEP，使用传统过渡态理论（TST）、正则变分过渡态理论（CVT）、微正则变分过渡态理论（muVT）、结合小曲率隧道效应（SCT）校正的CVT（CVT/SCT）以及结合埃卡特隧道效应校正的muVT（muVT/Eckart）来评估速率常数。从CHO基团提取氢的计算得到的CVT/SCT和muVT/Eckart速率常数的拟合三参数阿伦尼乌斯表达式分别为k CVT/SCT(T) = 4.92 x 10(-27).T 3.77.e(-7867.0/T)和k muVT/Eckart(T) = 2.10 x 10(-27).T(3.90).e(-7706.2/T)。从CH3基团提取氢的计算得到的CVT/SCT和muVT/Eckart速率常数的拟合三参数阿伦尼乌斯表达式分别为k(CVT/SCT)(T) = 1.27 x 10(-27).T(3.94).e(-14554.1/T)和k muVT/Eckart(T) = 1.62 x 10(-26).T(3.66).e(-15459.8/T)。
