Acta Phys. -Chim. Sin. ›› 2005, Vol. 21 ›› Issue (09): 961-966.doi: 10.3866/PKU.WHXB20050904

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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

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