CCl2自由基与H2O分子反应动力学研究

用213 nm激光光解CCl4产生CCl2自由基，用LP LIF技术测定了室温下基态CCl2自由基与H2O分子的反应速率常数为(5.45±0.95)×10－14 cm3•molecule－1•s－1.在G2MP2理论水平上计算了CCl2＋H2O反应的最低单重态势能面，揭示了插入与加成 消除两种反应机理，得到了三个可能的产物通道:HCl＋HClCO、HCl＋trans ClCOH以及HCl＋cis ClCOH.并用RRKM TST和传统过渡态理论计算了这三个通道的分支比及其温度效应.结果说明在低温下（273 K），插入机理的产物通道的分支比远大于加成 消除机理的产物通道， HCl＋HClCO是主要产物，分支比为77.4％，其次是HCl＋cis ClCOH，分支比为22.6％.而在高温下（3000 K），加成 消除机理的反应通道大于插入机理， HCl＋trans ClCOH分支比为82.3％.

Experimental and Theoretical Study on the Reaction of CCl2+H20

Absolute rate constant for the reaction of CCl2 radical with H2O is obtained as (5.45±0.95)×10－14 cm3•molecule－1•s－1 by LP LIF technique. The CCl2 is first produced by 213 nm laser photolysis of CCl4. The mechanism for the reaction CCl2＋H2O has been studied using a high level ab initio G2MP2 method. It is found that there are two reaction mechanisms: insertion and addition elimination. The three primary product channels, HCl＋HClCO， HCl＋trans ClCOH and HCl＋cis ClCOH, are studied in detail. Moreover, the branch ratios are calculated using RRKM TST and convention transition state theories. The calculations show that at lower temperatures the major product channel is HCl＋HCClO via the insretion of C atom of CCl2 into OH bond of H2O, whereas the formation of HCl＋trans ClCOH dominates at higher temperatures.