DOI QR코드

DOI QR Code

Theoretical Studies on the Base-Catalyzed Deprotonation of Sulfonyl-Activatec Carbon Acids

  • Published : 1997.02.20

Abstract

Theoretical AM1 MO studies are reported on the gas-phase deprotonations of N-methyl 4-((Y-phenylsulfonyl)pyridinium cations (Ⅳ) and N-(Y-benzyl) 4-((phenylsulfonyl)methyl pyridinium cations (Ⅴ) using NH3 as a base. Bronsted α values for deprotonation of Ⅳ and Ⅴ are 0.18 and 0.17, respectively. Bronsted β value of 0.53 is found for the deprotonation of Ⅳ and Ⅴ by substituted aniline bases. The negative transition state (TS) imbalances, Ⅰ(=α-β) < 0, are rationalized by the negative distance factor, Δd (=dp-dTS) < 0, where dp and dTS are the distance between anionic charge center and substituents in the product and in the TS, respectively. The inability of d-pπ-conjugation in Ⅳ, where instead n-σ* type sigma delocalization occurs, causes very little lag in the structural reorganization in the TS.

Keywords

References

  1. J. Am. Chem. Soc. v.105 Bordwell, F. G.;Boyle, W. J.
  2. J. Am. Chem. Soc. v.99 Jencks, D. A.;Jencks, W. P.
  3. J. Chem. Soc., Perkin Trans. v.2 Bell, R. P.;Grainger, S.
  4. J. Chem. Soc., Perkin Trans. v.2 Terrier, F.;Lelivere, J.;Chatrousse, A. P.;Farrell, P. G.
  5. J. Am. Chem. Soc. v.105 Bernasconi, C. F.;Hibdon, S. A.
  6. Acc. Chem. Res. v.20 Bernasconi, C. F.
  7. Adv. Phys. Org. Chem. v.27 Bernasconi, C. F.
  8. Bull. Korean Chem. Soc. Kim, W. K.;Chun, Y. I.;Sohn, C. K.;Kim, C. K.;Lee, I.
  9. J. Am. Chem. Soc. v.116 Wodzinski, S.;Bunting, J. W.
  10. J. Am. Chem. Soc. v.112 Stefanidis, D.;Bunting, J. W.
  11. J. Am. Chem. Soc. v.113 Stefanidis, D.;Bunting, J. W.
  12. J. Am. Chem. Soc. v.107 Dewar, M. J. S.;Zoebiech, E. G.;Healy, E. P.;Stewart, J. J. P.
  13. Theory and Practice of MO Calculations on Organic Molecules Csizmadia, I. G.
  14. MOPAC 6.0 Program, available from Quautum Chemistry Program Exchange (QCPE) NO. 506
  15. Science v.117 Leffler, J. E.
  16. J. Am. Chem. Soc. v.77 Hammond, G. S.
  17. Rates and Equilibria in Organic Reactions Leffler, J. E.;Grunwald, E.
  18. J. Org. Chem. v.52 Bernarsconi, C. F.;Panda, M.
  19. J. Org. Chem. v.52 Bernasconi, C. F.;Reufrow, R. A.
  20. Theoretical Aspects of Physical Organic Chemistry. The $S_N2$ Mechanism Shaik, S. S.;Sehlegel, H. B.;Wolfe, S.
  21. J. Am. Chem. Soc. v.108 Bors, D. A.;Streitwieser, Jr., A.
  22. Structural Theory of Organic Chemistry; Topics in Current Chemistry v.70 Epiotis, N. D.;Cherry, W. R.;Shaik, S.;Yates, R.;Bernardi, F.