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Quantum chemical study of reactions of episulfonium ions. 1. Comparative MNDO study of opening of the episulfonium ion ring by neutral nucleophiles and SN2 substitution in protonated methylthiol

  • V. I. Faustov
  • W. A. Smit
Physical Chemistry
  • 25 Downloads

Conclusions

  1. 1.

    From MNDO quantum chemical calculations, opening of the episulfonium ion ring by neutral nucleophiles X (X=NH3 and HCN) and related SN2 reactions of protonated methylthiol (PMT) with X proceed through formation of pre-reaction complexes in which X is coordinated either at the reacting C atom or (only in opening of episulfonium ion rings) at the center of the C-C bond.

     
  2. 2.

    In their electronic structure, the transition states for the reactions are reminiscent of a carbocation simultaneously reacting with the attacking and the leaving nucleophilic fragments (X ⋯\(\mathop C\limits^ + \) ⋯S).

     
  3. 3.

    Opening of episulfonium ion rings proceeds slightly more easily (Ea ∿ 10–12 kcal/mole) than substitution in PMT (Ea ∿ 22–25 kcal/mole). The ease of ring opening for episulfonium ions is due to the large exothermicity of the reaction and the lower internal activation barrier compared with SN2 reactions in PMT.

     

Keywords

Transition State Chemical Calculation Activation Barrier Ring Opening Chemical Study 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Literature cited

  1. 1.
    W. A. Smit, M. Z. Krimer, and E. A. Vorobieva, Tetrahedron Lett., 2451 (1975).Google Scholar
  2. 2.
    N. S. Zefirov, N. K. Sadovaya, A. M. Materremov, and I. V. Bodrikov, Zh. Org. Khim.,13, 903 (1976).Google Scholar
  3. 3.
    W. A. Smit, N. S. Zefirov, I. V. Bodrikov, and M. Z. Krimer, Acc. Chem. Res., 282 (1979).Google Scholar
  4. 4.
    D. Barton and W. D. Ollis, eds., Comprehensive Organic Chemistry, Vol. 2, Pergamon Press, New York (1979).Google Scholar
  5. 5.
    B. Badet, M. Julia, and M. Ramirez-Munos, Synthesis, 926 (1980).Google Scholar
  6. 6.
    K. Raghavachari, J. Chandrasekhar, and R. C. Burnier, J. Am. Chem. Soc.,106, 3124 (1984).Google Scholar
  7. 7.
    M. V. Bazilevskii, S. G. Koldobskii, and V. A. Tikhomirov, Usp. Khim.,55, 1667 (1986).Google Scholar
  8. 8.
    M. J. S. Dewar and W. Thiel, J. Am. Chem. Soc.,99, 4899 (1977).Google Scholar
  9. 9.
    M. J. S. Dewar and M. L. McKee, J. Comp. Chem.,4, 84 (1983).Google Scholar
  10. 10.
    M. J. S. Dewar and Ch. H. Reynolds, J. Comp. Chem.,7, 140 (1986).Google Scholar
  11. 11.
    G. Klopman (ed.), Chemical Reactivity and Reaction Paths, Wiley, New York (1974).Google Scholar
  12. 12.
    J. W. McIver, Jr. and A. Komornicki, J. Am. Chem. Soc.,94, 2625 (1972).Google Scholar
  13. 13.
    G. S. Hammond, J. Am. Chem. Soc.,77, 334 (1955).Google Scholar
  14. 14.
    A. C. Knipe, in: The Chemistry of the Sulphonium Group, Pt. 1 (C. J. M. Stirling and S. Patai, eds.), Wiley, New York (1981).Google Scholar
  15. 15.
    M. Meot-Ner, P. Hamlet, E. P. Hunter, and F. H. Field, J. Am. Chem. Soc.,102, 6392 (1980).Google Scholar
  16. 16.
    P. Kebarle, Ann. Rev. Phys. Chem.,28, 445 (1977).Google Scholar
  17. 17.
    J. W. Albert, Ann. Rev. Phys. Chem.,31, 2706 (1980).Google Scholar
  18. 18.
    G. P. Ford and C. T. Smith J. Am. Chem. Soc.,109, 1325 (1987).Google Scholar
  19. 19.
    J. Hayami, N. Tanaka, N. Hihara, and A. Kaji, Tetrahedron Lett., 385 (1973).Google Scholar
  20. 20.
    J. Chandrasekhar, S. F. Smith, and W. L. Jorgensen, J. Am. Chem. Soc.,106, 3049 (1984).Google Scholar

Copyright information

© Plenum Publishing Corporation 1990

Authors and Affiliations

  • V. I. Faustov
    • 1
  • W. A. Smit
    • 1
  1. 1.N. D. Zelinskii Institute of Organic ChemistryAcademy of Sciences of the USSRMoscow

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