Bulletin of the Korean Chemical Society

Korean Chemical Society (대한화학회)
권호 표지
DOI QR코드

DOI QR Code

Stoichiometric Solvent Effect on SN1 Solvolytic Reactivity Accounting for Phenomenon of Maximum Rates in Methanol-Nitromethane Mixtures

  • Published : 2004.09.20
Download PDF
⟨ Previous Next ⟩

Abstract

Pseudo-first order rate constants $(k_{obs})$ are reported for the following solvolyses in approximately isodielectric mixtures: 3- and 4-methoxybenzyl chloride, bromo- and chlorodiphenylmethane, and 4-chloro-, 4,4'-dichloro and 4-methyl-chlorodiphenylmethane in 0-80% v/v nitromethane-methanol mixtures; and bromo- and chlorodiphenylmethane and 4-methyl-chlorodiphenylmethane in various acetonitrile-methanol mixtures (in the range 0-50% v/v) at$25^{\circ}C.$ These data, and literature data for t-butyl halides (Cl, Br, and I), and for p-methoxybenzoyl chloride, show rate maxima in solvent compositions of ca. 30% aprotic cosolvent, explained by a stoichiometric solvent effect on electrophilic solvation. Linear relationships are observed between $(k_{obs})/[MeOH]^2$ and [AP]/[MeOH], where [AP] refers to the molar concentration of aprotic cosolvent. The results are consistent with competing third order contributions to $k_{obs}$, $k_{MM}[MeOH]^2$ with hydrogen-bonded methanol as electrophile, and $k_{MAP}[MeOH][AP]$ with hydrogen-bonding disrupted by the aprotic solvent.

Keywords

References

  1. Reichardt, C. Solvents and Solvent Effects in Organic Chemistry,2nd ed; VCH: Weinheim, Germany, 1988;Chapter 7
  2. Reichardt, C. Solvents and Solvent Effects in Organic Chemistry, 2nd ed; VCH: Weinheim, Germany, 1988, p 196-203
  3. Reichardt, C. Solvents and Solvent Effects in Organic Chemistry, 2nd ed; VCH: Weinheim, Germany, 1988, p 139
  4. Bentley, T. W.; Llewellyn, G. Prog. Phys. Org. Chem. 1990, 17,121. https://doi.org/10.1002/9780470171967.ch5
  5. Kevill, D. N. In Advances in Quantitative Structure-PropertyRelationships; Charton, M., Ed.; JAI Press: Greenwich, CT, 1996;Vol. 1, p 81.
  6. Kevill, D. N.; Anderson, S. W.; Ismail, N. H. J. J. Org. Chem.1996, 61, 7256. https://doi.org/10.1021/jo960909t
  7. Bentley, T. W.; Jones, R. O. J. Chem. Soc., Perkin Trans. 2 1993,2351.
  8. Ryu, Z. H.; Lim, G. T.; Bentley, T. W. Bull. Korean Chem. Soc.2003, 24, 1293. https://doi.org/10.5012/bkcs.2003.24.9.1293
  9. Bentley, T. W.; Harris, H. C. J. Org. Chem. 1988, 53, 724. https://doi.org/10.1021/jo00239a004
  10. Koo, I. S.; Yang, K.; Kang, K.; Lee, I.; Bentley, T. W. J. Chem.Soc., Perkin Trans. 2 1998, 1179.
  11. Luton, P. R.; Whiting, M. C. J. Chem. Soc., Perkin Trans. 2 1979,1507.
  12. Kevill, D. N.; Bahari, M. S. J. Chem. Soc., Chem. Comm. 1982,572.
  13. Kevill, D. N.; Wang, A. J. Chem. Soc., Chem. Comm. 1981, 83.
  14. Lee, I.; Sung, D. D.; Uhm, T. S.; Ryu, Z. H. J. Chem. Soc., PerkinTrans. 2 1989, 1697.
  15. Lee, I.; Lee, H. W.; Uhm, T. S.; Sung, D. D.; Ryu, Z. H. J. KoreanChem. Soc. 1988, 274.
  16. Shon, S. C. PhD Thesis, Inha University, 1985.
  17. Bentley, T. W.; Koo, I. S.; Norman, S. J. Org. Chem. 1991, 56,1604. https://doi.org/10.1021/jo00004a048
  18. Nishida, S. J. Org. Chem. 1967, 32, 2692. https://doi.org/10.1021/jo01284a600
  19. Nishida, S. J.Org. Chem. 1967, 32, 2695. https://doi.org/10.1021/jo01284a010
  20. Winstein, S.; Fainberg, A. H.; Grunwald, E. J. Am. Chem. Soc.1957, 79, 4147.
  21. Bartlett, P. D.; Nebel, R. W. J. Am. Chem. Soc. 1940, 62, 1345. https://doi.org/10.1021/ja01863a005
  22. Gelles, E.; Hughes, E. D.; Ingold, C. K. J. Chem. Soc. 1954, 2918. https://doi.org/10.1039/jr9540002918
  23. Brown, H. C.; Okamoto, Y. J. Am. Chem. Soc. 1958, 80, 4979. https://doi.org/10.1021/ja01551a055
  24. DiLabio, G. A.; Ingold, K. U. J. Org. Chem. 2004, 69, 1620. https://doi.org/10.1021/jo035693r
  25. Bentley, T. W.; Llewellyn, G.; Ryu, Z. H. J. Org. Chem. 1998, 63,4654. https://doi.org/10.1021/jo980109d
  26. Taft, R. W. Prog. Phys. Org. Chem. 1981, 13, 485. https://doi.org/10.1002/9780470171929.ch6
  27. Brown, H. C.; Fletcher, R. S. J. Am. Chem. Soc. 1949, 71,1845. https://doi.org/10.1021/ja01173a093
  28. Bentley, T. W.; Ryu, Z. H. J. Chem. Soc., Perkin Trans. 2 1994,761.
  29. Ryu, Z. H.; Shin, S. H.; Lim, K. T.; Lee, J. P. Bull. Korean Chem.Soc. 2004, 25, 307. https://doi.org/10.5012/bkcs.2004.25.2.307