Use of kinetic isotope effects in mechanism studies. Isotope effects and element effects associated with Hydron-Transfer steps during alkoxide-promoted dehydrohalogenations

Journal of the American Chemical Society

Volumn 119, Issue 42, 1997, Pages 9965-9974

  Koch, Heinz F ^a   Lodder, Gerrit ^b   Koch, Judith G ^c   Bogdan, David J ^c   Brown, Geoffrey H ^c   Carlson, Carrie A ^c   Dean, Amy B ^c   Hage, Ronald ^c   Han, Patrick ^c   Hopman, Johan C P ^c   James, Lisa A ^c   Knape, Petra M ^c   Roos, Eric C ^c   Sardina, Melissa L ^c   Sawyer, Rachael A ^c   Scott, Barbara O ^c   Testa III, Charles A ^c   Wickham, Steven D ^c  

^a ITHACA COLLEGE   (United States)

^b LEIDEN UNIVERSITY   (Netherlands)

^c NONE

Author keywords

[No Author keywords available]

Indexed keywords

ALCOHOL; METHANOL; ORGANOHALOGEN DERIVATIVE; SOLVENT;

ARTICLE; CHEMICAL REACTION; CHEMICAL REACTION KINETICS; DEHALOGENATION; HYDROGEN BOND; PROTON TRANSPORT; REACTION ANALYSIS;

EID: 9844268507     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja970189n     Document Type: Article

References (61)

1. Part 4: Koch, H. F.; McLennan, D. J.; Koch, J. G.; Tumas, W.; Dobson, B.; Koch, N.H. J. Am. Chem. Soc. 1983, 105, 1930.
2. (a) Summer research student at Leiden from Ithaca College. (b) Summer research student at Ithaca from the University of Leiden. (c) Summer research student at Leiden from Oberlin College.
3. Koch, H. F.; Dahlberg, D. B.; Toczko, A. G.; Solsky, R. L. J. Am. Chem. Soc. 1973, 95, 2029.
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10. (b) The exponent for the Swain-Schaad relationship used in ref 9a is 2.344.
11. Koch, H. F.; Dahlberg, D. B. J. Am. Chem. Soc. 1980, 102, 6102.
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14. D.
15. Since the ρ values of the other reactions are larger than those reported in the phenethyl series, the smaller PKIE values would suggest later rather than earlier transition structures.
16. Kaldor, S. B.; Saunders, W. H., Jr. J. Am. Chem. Soc. 1979, 101, 7594.
17. 2Br kinetics.
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22. Reference 1, pp 1935 and 1936.
23. X is 500 ca/mol and for loss of HBr 1800 cal/mol.
24. We thank Duncan McLennan, Auckland University in New Zealand, for a copy of his program that models the Arrhenius behavior of primary kinetic isotope effects for a reaction that features an internal-return mechanism. The program makes use of eq 2 and a similar one for protium and tritium. The original program, in Fortran, was converted to Turbo Pascal for use with a PC, and can be obtained from J. G. Koch.
25. H = 66 cal/mol.
26. -1 = 2.0 is better.
27. D = 4.57.
28. 4CT=CHCl and resulted in good kinetics.
29. T = 0.0049 ± 0.0003.
30. -1 is found for several similar systems.
31. 1 suggests negative ion hyperconjugation in the transition structure since the electronegativity of Cl vs Br should give the reverse order. The same would hold true for the case of F vs Cl. A publication that appeared after this manuscript was submitted gives additional computational evidence for negative ion hyperconjugation by a β C-F [Sanuders, W. H., Jr. J. Org. Chem. 1997, 62, 244].
32. Gold, V.; Grist, S. J. Chem. Soc. (B) 1971, 2282.
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35. (c) Gold, V.; Morris, K. P.; Wilcox, C. F. J. Chem. Soc., Perkin Trans. 2 1982, 1615.
36. The measurement of kinetic solvent isotope effect for these reactions has not been as extensive. However, the few that we have measured are about 2.0.
37. See ref 17, pp 5425-27.
38. Koch, H. F.; Danlberg, D. B.; Lodder, G.; Root, K. S.; Touchette, N. A.; Solsky, R.L.; Zuck, R. M.; Wagner, L. J.; Koch, N. H.; Kuzemko, M. A. J. Am. Chem. Soc. 1983, 105, 2394.
39. Cristol, S. J.; Hause, N. L.; Meek, J. S. J. Am. Chem. Soc. 1951, 73, 674.
40. Drysdale, J. J.; Phillips, W. D. J. Am. Chem. Soc. 1957, 79, 319.
41. iHBr [Koch, H. F. In Comprehensive Carbanion Chemistry, Part C; Buncel, E., Durst, T., Eds.; Elsevier: Amsterdam, 1987; pp 333 and 334.]
42. (a) Thompson, D. S.; Newmark, R. A.; Sederholm, C. H. J. Chem.Phy. 1962, 37, 411.
43. (b) Weigert, F. J.; Winstead, M. B.; Garrets, J. I.; Roberts. J. D. J. Am. Chem. Soc. 1970, 92, 7359.
44. One of the referees commented that this would be at odds with the Curtin-Hammett principle. Although this is true, the energetics of the rotational barriers and the competition with internal return may well be an example of the breakdown of this principle, which does not have a large amount of experimental backing.
45. 2 increases to 3.92 ± 0.04 at 0°C.
46. ‡.
47. Reference 1, p 1934, has a full discussion of this with additional references.
48. Dagger; = 14.3 ± 0.3. Justin C. Biffinger, unpublished results.
49. 5CHBrCFClBr and the fastest being the other diastereomer [Koch, H. F. In Comprehensive Carbanion Chemistry: Ground and Excited State Reactivity; Buncel, E., Durst, T., Eds.; Elsevier: Amsterdam, 1987; Part C, Chapter 6, p 330-335].
50. -1.
51. (a) Sano, T; Tatsumoto, N.; Niwa, T.; Yasunaga, T. Bull. Chem. Soc. Jpn. 1972, 45, 2669.
52. (b) Sano, T.; Tatsumoto, N.; Mende, Y.; Yasunaga, T. Bull. Chem. Soc. Jpn. 1972, 45, 2673.
53. Saunders, W. H., Jr. Acc. Chem. Res. 1976, 9, 19.
54. 2 hybridization."
55. Reference 11, p 6106.
56. The extent of reaction has also been followed by the disappearance of the OH proton using proton NMR.
57. Herkes, F. E.; Burton, D. J. J. Org. Chem. 1967, 32, 1311.
58. Roberts, R. M.; Gilbert, J. C.; Rodewald, L. B.; Wingrove, A. S. An introduction to Modern Experimental Organic Chemistry, 2nd ed.; Holt, Rinehart and Winston. Inc.: New York, 1974; pp 323 and 324.
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60. Buckles, R. E.; Long, J. W. J. Am. Chem. Soc. 1951, 73, 998.
61. Burton, D. J.; Anderson, A. L.; Takei, R.; Koch, H. F.; Shih, T. L. J. Fluorine Chem. 1980, 16, 229.