Bulletin of the Korean Chemical Society

Korean Chemical Society (대한화학회)
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Ab Initio Study on the Thermal Decomposition of CH3CF2O Radical

  • Published : 2009.12.20
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Abstract

The decomposition reaction mechanism of $CH_3CF_2O$ radical formed from hydroflurocarbon, $CH_3CHF_2$ (HFC-152a) in the atmosphere has been investigated using ab-initio quantum mechanical methods. The geometries of the reactant, products and transition states involved in the decomposition pathways have been optimized and characterized at DFT-B3LYP and MP2 levels of theories using 6-311++G(d,p) basis set. Calculations have been carried out to observe the effect of basis sets on the optimized geometries of species involved. Single point energy calculations have been performed at QCISD(T) and CCSD(T) level of theories. Out of the two prominent decomposition channels considered viz., C-C bond scission and F-elimination, C-C bond scission is found to be the dominant path involving a barrier height of 12.3 kcal/mol whereas the F-elimination path involves that of a 28.0 kcal/mol. Using transition-state theory, rate constant for the most dominant decomposition pathway viz., C-C bond scission is calculated at 298 K and found to be 1.3 ${\times}$ 10$^4s{-1}$. Transition states are searched on the potential energy surfaces involving both decomposition channels and each of the transition states are characterized. The existence of transition states on the corresponding potential energy surface are ascertained by performing Intrinsic Reaction Coordinate (IRC) calculation.

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References

  1. Molina, M. J.; Rowland, F. S. Nature 1974, 249, 810 https://doi.org/10.1038/249810a0
  2. Anderson, J. G.; Toohey, D. W.; Brune, W. H. Science 1991, 39, 251
  3. Rowland, F. S. Ambio. 1990, 19, 281
  4. Rowland, F. S.; Molina, M. J. Chem. Eng. News. 1994, 8, 72
  5. Hoffman, J. S. Ambio. 1990, 19, 329
  6. Solomon, S. Nature 1990, 347, 6291 https://doi.org/10.1038/347347a0
  7. Rowland, F. S. Ann. Rev. Phys. Chem. 1991, 42, 731 https://doi.org/10.1146/annurev.pc.42.100191.003503
  8. Atkinson, R. In Scientific Assessment of Stratospheric Ozone, Vol II. World Meteorological Organization Global Ozone Research and Monitoring Project report No-20, 1989
  9. World Meteorological Organization. Scientific Assessment of Ozone Depletion Report No 47, Global Ozone Research and Monitoring Project, 2002
  10. Gierczak, T.; Talukdar, R.; Vaghjiani, G. L.; Lovejoy, E. R.; Ravishankara, A. R. J. Geophys. Rev. 1991, 96, 5001 https://doi.org/10.1029/90JD02736
  11. Atkinson, R. J. Phys. Chem. 1989, 18, 1 https://doi.org/10.1021/j150145a001
  12. Brasseur, G. P.; Orlando, J. J. Atmospheric Chemistry and Global Change; Oxford University Press: New York, 1999
  13. Wallington, T. J.; Hurley, M. D. Francheboud, J. M.; Orlando, J. J.; Tyndall, G. S.; Sehested, J.; Mogelberg,T. E.; Nielsen, O. J. J. Phys. Chem. 1996, 100, 18116 https://doi.org/10.1021/jp9624764
  14. Wallington, T. J.; Hurley, M. D.; Anderson, M. P.; Toft, A. J. Phys. Chem A 2005, 109, 9061 https://doi.org/10.1021/jp052270f
  15. Hehre, W. J.; Radom, L.; Schleyer, P. V. R.; Pople, J. A. Ab Initio Molecular Orbital Theory; Wiley: New York. 1986
  16. Frisch, M. J. et al. Gaussian 03 (Revision C.02); Gaussian Inc.; Wallingford, CT, 2004
  17. Becke, A. D. J. Chem. Phys. 1993, 98, 5648 https://doi.org/10.1063/1.464913
  18. Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. 1988, 37, 785 https://doi.org/10.1103/PhysRevB.37.785
  19. Gonzalez, C.; Schlegel, H. B. J. Chem. Phys. 1989, 90, 2154 https://doi.org/10.1063/1.456010
  20. Gonzalez, C.; Schlege, H. B. J. Chem. Phys. 1990, 94, 5523 https://doi.org/10.1021/j100377a021
  21. Pople, J. A.; Head-Gordan, M.; Raghavachari, K. J. Chem, Phys. 1987, 87, 5968 https://doi.org/10.1063/1.453520
  22. Watts, J. D.; Gauss, J.; Bartlett, R. J. Chem. Phys. Lett. 1992, 200, 1 https://doi.org/10.1016/0009-2614(92)87036-O
  23. Frisch, A.; Nielsen, A. B.; Holder, A. J. GaussView Users Manual; Gaussian Inc.: 2000
  24. Hou, H.; Wang, B. Phys. Chem. Chem. Phys. 2000, 2, 61 https://doi.org/10.1039/a907481c
  25. Truhlar, D. G.; Garrett, B. C.; Klippenstein, S. J. J. Phys. Chem. 1996, 100, 12771 https://doi.org/10.1021/jp953748q
  26. Wigner, E. P. Z. Phys. Chem. 1932, B19, 203
  27. Stevens, J. E.; Khayat, R. A. J.; Radkevich, O.; Brown, J. J. Phys. Chem. 2004, 108, 11354 https://doi.org/10.1021/jp0468509
  28. Caralp, F.; Devolder, P.; Fittschen, C.; Gomez, N.; Hippler, H.; Mereau, R.; Rayez, M. T.; Striebel, F.; Viskolcz, B. Phys. Chem. Chem. Phys. 1999, 1, 2935 https://doi.org/10.1039/a901768b

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