1,1-二氟乙烷与氟原子反应的机理研究和速率常数计算

Rate Constant Calculation of the Hydrogen Abstraction Reaction of Fluorine Atom with 1,1-Difluoroethane

采用双水平直接动力学方法研究了反应CH3CHF2＋F→产物的反应机理和动力学性质.该反应存在3个反应通道,即1个α-氢迁移和2个β-氢迁移反应通道.在MP2/6-311G（d,p）水平下优化了所有稳定点的几何构型,在G3（MP2）//MP2水平下,对反应路径上的一系列点进行了单点能量校正.根据变分过渡态理论计算了该反应在200~2 000 K温度区间的速率常数,并与实验值进行了对比.计算结果表明β-氢提取通道在整个温度区间是主要的反应通道.

The dynamic properties of the multi-channel hydrogen abstraction reaction of CH3CHF2 ＋ F → products are studied by dual-level direct dynamics method.Three reaction channels,one for α-hydrogen abstraction and two for β-hydrogen abstractions,are identified.The minimum energy paths（MEPs） of all reaction channels are calculated at the MP2/6-311G（d,p） level and the energy profiles along the MEPs are further refined at the G3（MP2）//MP2 level.By canonical variational transition state theory（CVT） the rate constants are calculated incorporating the small-curvature tunneling（SCT） correction in the temperature range of 200～2 000 K.The comparison of the rate constants with available experimental value is discussed.The calculated results show that the β-hydrogen abstraction channel is the major reaction pathway in the whole temperatures.