Lifetimes of imidinium ions in aqueous solution

Journal of the American Chemical Society

Volumn 119, Issue 31, 1997, Pages 7271-7280

  Dalby, Kevin N ^a,b   Jencks, William P ^a  

^a BRANDEIS UNIVERSITY   (United States)

^b UNIVERSITY OF TEXAS AT AUSTIN   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

AMIDINE;

ARTICLE; DRUG STABILITY; IONIC STRENGTH; IONIZATION; TEMPERATURE;

EID: 0030792295     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja970628i     Document Type: Article

References (58)

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2. (b) Song, B. D.; Jencks, W. P. Ibid. 1989, 111, 8470.
3. Richard, J. P. Tetrahedron 1994, 51, 1535.
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11. (b) Richard, J. P.; Jencks, W. P. Ibid. 1982, 104, 4689.
12. (a) Fishbein, J. C.; McClelland, R. A. J. Am. Chem. Soc. 1987, 109, 2824.
13. (b) Amyes, T. A.; Jencks, W. P. Ibid. 1988, 110, 3677.
14. (c) Amyes, T. L.; Jencks, W. P. Ibid. 1989, 111, 7888.
15. (d) Nagorski, R. W.; Brown, R. S. Ibid. 1992, 114, 7773.
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25. McClelland, R. A.; Cozenns, F. L.; Steenken, S. Amyes, T. L.; Richard, J. P. J. Chem. Soc., Perkin Trans. 2 1993, 1717.
26. The hydrolysis of 12-F was too slow to study conveniently, and therefore the chloroformamidine was used.
27. Below pH 4 compounds 1-F and 3-F have been shown to hydrolyze through an alternative pathway in which the transition state for the hydrolysis contains an extra proton (K. N. Dalby and W. P. Jencks, unpublished results). The mechanism for this process is believed to involve the hydrolysis of the fluoroformamidinium ion and is not significant above pH 8 for any of the compounds studied. At pH 9.3 the solvolysis of the compounds studied is pH independent. A reaction of 3-F with hydroxide ion becomes significant at 0.01 M hydroxide ion.
28. dgare Brønsted type correlations for the dependence of rate constants on the pK of the parent primary aniline or secondary amine, respectively.
29. Guthrie, R. D.; Jencks, W. P. Acc. Chem. Res. 1989, 22, 343.
30. Richard, J. P.; Rothenberg, M. E.; Jencks, W. P. J. Am. Chem. Soc. 1984, 106, 1361.
31. -] is linear for all the fluoroformamidines studied.
32. Kandanarachchi, P.; Sinnott, M. L. J. Am. Chem. Soc. 1994, 116, 5592.
33. (a) Ritchie, C. D.; Wright, D. J.; Huang D.-S.; Kamego, A. A. J. Am. Chem. Soc. 1975, 97, 1163.
34. (b) Young, P. R.; Jencks, W. P. Ibid. 1977, 99, 8238.
35. (c) Gandler, J. Ibid. 1985, 107, 8218.
36. s is not a salt effect.
37. The final product of trapping by 2-hydroxyetbanethiolate, presumably the C-O adduct, is stable.
38. solv. The concentration of 2-hydroxyethanethiolate anion was therefore kept below 2 mM, in order to maintain first order kinetics.
39. -1 in the presence of 0.2 M and 0.083 M fluoride ion, respectively.
40. Ritchie, C. D.; Gandler, J. J. Am. Chem. Soc. 1970, 101, 7318.
41. -1. In the presence of organic cosolvents and fluoride ion these reactions could become significant at pH 9.3.
42. s in 45% glycerol indicates that it has been significantly (>4-fold) depressed in 45% glycerol.
43. 4, respectively.
44. 10e
45. dg < -0.20.
46. 5b This scale predicts a difference in reactivity toward a carbocation of of ∼107 between azide anion and water.
47. + is partially diffusion-controlled in this solvent.
48. 12 and the rate constants reported in Table 1 will be overestimates by a factor of approximately 2-fold.
49. McClelland, R. A.; Banait, N.; Steenken, S. J. Am. Chem. Soc. 1986, 108, 7023.
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53. Ritchie, C. D.; Virtanen, P. O. I. J. Am. Chem. Soc. 1972, 94, 1589.
54. -1 (see Table 1). The variation in the structure of the amine substituents also suggests that this value should be treated with caution.
55. Hegarty, A. F.; Cronin, J. D.; Scott, F. L. J. Chem. Soc., Perkin Irons. 2 1975, 429.
56. Kühle, E. Angew. Chem., Int. Ed. Engl. 1962, 1, 647.
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58. See Royer R. E.; Daub, G. H.; Vander Jagt, D. L. J. Org. Chem. 1979, 44, 3196, for a similar approach.