Steric Assistance in Solvolytic Processes

  • Herbert C. Brown


The dissociation of molecular addition compounds provided a powerful new tool to explore steric effects in organic molecules.1,2 To illustrate the application of this tool, the behavior of trimethylamine and triethylamine with trimethylborane may be reviewed. Triethylamine (pKa 10.75) is a somewhat stronger base than trimethylamine (pKa 9.75). Consequently, one would anticipate that the stronger base would form the more stable addition compound with the Lewis acid. However, the reverse is true: ΔH dissoc.(CH3)3N:B(CH3)3, 17.6 kcal mol−1: ΔH dissoc.(C2H5)3N:B(CH3) 3,~10kcal mol−1


Sodium Borohydride Steric Effect Addition Compound Methine Carbon Steric Strain 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    H. C. Brown, J. Chem. Ed.36, 424 (1959).CrossRefGoogle Scholar
  2. 2.
    H. C. Brown, Boranesin Organic Chemistry, Cornell University Press, Ithaca, N.Y., 1972, Chapters V-VIII.Google Scholar
  3. 3.
    H. C. Brown and S. Sujishi, J. Amer. Chem. Soc., 70, 2878 (1948).CrossRefGoogle Scholar
  4. 4.
    H. C. Brown, Science, 103, 385 (1948).CrossRefGoogle Scholar
  5. 5.
    H. C. Brown and R. S. Fletcher, J. Amer. Chem. Soc., 70, 1845 (1948).Google Scholar
  6. 6.
    H. C. Brown and H. L. Berneis, J. Amer. Chem. Soc., 75, 10 (1953).CrossRefGoogle Scholar
  7. 7.
    P. D. Bartlett and T. T. Tidwell, J. Amer. Chem. Soc., 90, 4421 (1968).CrossRefGoogle Scholar
  8. 8.
    H. C. Brown and W. C. Dickason, J. Amer. Chem. Soc., 91, 1226 (1969).CrossRefGoogle Scholar
  9. 9.
    H. C. Brown and J. Muzzio, J. Amer. Chem. Soc., 88, 2811 (1966).CrossRefGoogle Scholar
  10. 10.
    E. N. Peters and H. C. Brown, J. Amer. Chem. Soc., 97, 2892 (1975).CrossRefGoogle Scholar
  11. 11.
    J. L. Fry, E. M. Engler, and P. v. R. Schleyer, J. Amer. Chem. Soc., 94, 4628 (1972).CrossRefGoogle Scholar
  12. 12.
    G. D. Sargent, Quart. Revs., 20, 301 (1966).CrossRefGoogle Scholar
  13. 13.
    S. Ikegami, D. L. Vander Jagt, and H. C. Brown, J. Amer. Chem. Soc., 90, 7124 (1968).CrossRefGoogle Scholar
  14. 14.
    H. C. Brown and S. Ikeganii, J. Amer. Chem. Soc., 90, 7122 (1968).CrossRefGoogle Scholar
  15. 16.
    H. C. Brown, J. H. Brewster, and H. Shechter, J. Amer. Chem. Soc., 76, 467 (1954).CrossRefGoogle Scholar
  16. 17.
    H. C. Brown and M. Borkowski, J. Amer. Chem. Soc., 74, 1894 (1952).CrossRefGoogle Scholar
  17. 18.
    R. Heck and V. Prelog, Helv. Chima Acta, 38,1541 (1955).CrossRefGoogle Scholar
  18. 19.
    H. C. Brown and G. Ham, J. Amer. Chem. Soc., 78, 2735 (1956).CrossRefGoogle Scholar
  19. 20.
    H. C. Brown and K. Ichikawa, Tetrahedron, 1, 221 (1957).CrossRefGoogle Scholar
  20. 22.
    R. C. Bingham and P. v. R. Schleyer, J. Amer. Chem. Soc., 93,3189 (1971)CrossRefGoogle Scholar
  21. W. Parker, R. L. Tranter, C. I. F. Watt, L. W. K. Chang, and P. v. R. Schleyer, ibid., 96, 7121 (1974).Google Scholar
  22. 23.
    P. v. R. Schleyer,private Communication to H. C. Brown; W. L. Dilling, C. E. Reineke, and R. A. Plepys, J. Org. Chem., 34, 2605 (1969).CrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1977

Authors and Affiliations

  • Herbert C. Brown
    • 1
  1. 1.Purdue UniversityWest LafayatteUSA

Personalised recommendations