水辅助下的OH自由基与CH_3OOH气相反应机理的理论研究

利用量子化学计算方法对单个水分子不存在与存在的情况下OH自由基与CH3OOH的气相氢抽取反应进行了理论研究.在BHand HLYP/6-311++G(2df,2pd)理论水平下优化了所有驻点的几何构型,在此基础上利用CCSD(T)/cc-p VTZ方法对所有驻点的单点能重新进行了计算.计算结果表明,OH自由基与CH3OOH反应的主要通道是OH自由基抽取CH3OOH中的-OH基团上的H原子.在单个水分子存在的情况下,反应的主要通道没有改变,但是水化过渡态的能量显著地降低,显然单个水分子对OH+CH3OOH反应具有催化效应.

Theoretical study on the gas phase reaction mechanism for the water-assisted reaction of OH radical with CH3OOH

The gas-phase hydrogen abstraction reaction mechanism between the OH radical and CH3OOH without and with a single water molecule is investigated theoretically using quantum chemical method. The geometries of all stationary points are optimized at the BHandHLYP/6-311++G(2df,2pd) level, and their single-point energies are refined at the CCSD(T)/cc-pVTZ level of theory. The calculation results indicate that the abstraction of the hydrogen from the -OH group in CH3OOH by the hydroxyl radical is the major pathway for the OH+CH3OOH reaction. When one water molecule is added, the major pathway of the reaction does not change. However, the energy of the hydrated transition states for the hydrogen abstraction reactions is significantly lowered compared to that of the nonhydrated ones. Clearly, a single water molecule has a catalytic effect on the OH+CH3OOH reaction.