物理化学学报 >> 2003, Vol. 19 >> Issue (06): 481-486.doi: 10.3866/PKU.WHXB20030601

研究论文    下一篇

CCl2自由基与H2O分子反应动力学研究

刘云珍;胡长进;裴林森;陈从香;马兴孝   

  1. 中国科学院选键化学开放实验室， 中国科学技术大学化学物理系，合肥　230026
  • 收稿日期:2002-10-14 修回日期:2003-02-26 发布日期:2003-06-15
  • 通讯作者: 陈从香 E-mail:cxchen@ustc.edu.cn

Experimental and Theoretical Study on the Reaction of CCl2＋H2O

Liu Yun-Zhen;Hu Chang-Jin;Pei Lin-Sen;Chen Cong-Xiang;Ma Xing-Xiao   

  1. Open Laboratory of Bond Selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, Hefei　230026
  • Received:2002-10-14 Revised:2003-02-26 Published:2003-06-15
  • Contact: Chen Cong-Xiang E-mail:cxchen@ustc.edu.cn

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摘要： 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％.

关键词: CCl2自由基, 速率常数, Ab initio理论计算, RRKM(RiceRamspergerKasselMarcus)理论

Abstract: 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.

Key words: CCl2 radical, Rate constant, Ab initio theoretical calculation,