物理化学学报 >> 2005, Vol. 21 >> Issue (09): 961-966.doi: 10.3866/PKU.WHXB20050904

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Cl2+2HI=2HCl+I2反应机理的理论研究

刘红艳; 王遵尧; 刘树深   

  1. 桂林工学院材料与化学工程系, 桂林 541004； 南京大学环境学院, 南京 210093； 盐城工学院化工系, 江苏 盐城 224003
  • 收稿日期:2005-01-04 修回日期:2005-02-21 发布日期:2005-09-15
  • 通讯作者: 王遵尧 E-mail:wangzun315@163.com

Theoretical Study on the Reaction Mechanism of Cl2+2HI=2HCl+I2

LIU Hong-yan; WANG Zun-yao; LIU Shu-shen   

  1. Department of Material and Chemical Engineering, Guilin Institute of Technology, Guilin 541004; School of the Environment, Nanjing University, Nanjing 210093; Department of Chemical Engineering, Yancheng Institute of Technology, Yancheng 224003
  • Received:2005-01-04 Revised:2005-02-21 Published:2005-09-15
  • Contact: WANG Zun-yao E-mail:wangzun315@163.com

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摘要： 分别在MP2/3-21G**、CCSD(T)/3-21G**//MP2/3-21G**和B3LYP/3-21G**3种水平上, 计算研究了气相反应Cl2+2HI=2HCl+I2的机理, 求得一系列四中心和三中心的过渡态. 通过比较六种反应通道的活化能大小, 得到了相同的结论：双分子基元反应Cl2+HIHCl+ICl和ICl+HII2+HCl的最小活化能小于Cl2、HI和ICl的解离能, 从理论上证明了反应Cl2+2HI=2HCl+I2将优先以分子与分子作用形式分两步完成. 用内禀反应坐标(IRC)验证了MP2/3-21G**方法计算得到的过渡态.

关键词: 氯, 碘化氢, Ab initio, 反应机理, 双分子反应

Abstract: The gas phase reaction mechanism of Cl2+2HI=2HCl+I2 has been investigated by MP2/3-21G**, CCSD(T) /3-21G**//MP2/3-21G** and B3LYP/3-21G** levels respectively, and a series of four-centred and three-centred transition states have been obtained. The following result is achieved by comparing the activation energies of six reaction paths. The activation energies of the bimolecular elementary reactions Cl2+HIHCl+ICl and ICl+HII2+HCl are lower than the dissociation energies of Cl2, HI, and ICl. It is thus theoretically proved that the titled reaction occurs more easily in the bimolecular form with two intermediate steps. And finally the transition state calculated from MP2/3-21G** method is validated by intrinsic reaction coordinate (IRC).

Key words: Chlorine, Hydrogen iodide, Ab initio, Reaction mechanism, Bimolecular reaction