三氯乙烷与氟原子的反应机理研究和速率常数计算

采用双水平直接动力学方法研究了反应CH3CCl3+F→CH2CCl3+HF的反应机理和动力学性质;在MPW1K/6-311+G(d,p)水平上优化了所有稳定点的几何构型,并通过频率分析进行了验证;随后在MCG3-MPWPW91//MPW1K水平上进行了能量校正,并利用变分过渡态理论,在MCG3-MPWPW91//MPW1K/6-311+G(d,p)水平上计算了反应在200～2 000K温度区间内的速率常数.结果表明,反应物CH3CCl3属于Cs点群,-CH3基团上的3个H原子等同,反应存在单个氢迁移反应通道.

Study on reaction mechanism of trichloroethane and fluorine atom as well as calculation of rate constant

The mechanism and dynamical properties for the hydrogen-Abstraction reaction of 1,1,1-trichloroethane with fluorine atom over the temperature range of 200-2 000 K were investigated with dual-level direct dynamics method.The geometric configurations of all stable points were optimized at the MPW1K/6-311＋G（d,p） level and verified by frequency analysis.Moreover,energy calibration was conducted at the MCG3-MPWPW91//MPW1K level,and the rate constant of the reaction over a wide temperature range of 200-2 000 K was estimated based on canonical variational transition state theory at the MCG3-MPWPW91//MPW1K/6-311＋G（d,p） level.Path for the reaction was obtained theoritically.Results indicate that reactant CH3CCl3 belongs to Cs point group,and the three hydrogen atoms of-CH3 radical are identical,which allows the reaction to proceed via single-H transfer reaction channel.