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Volumn 72, Issue 25, 2007, Pages 9663-9668

Dramatic acceleration of the Menschutkin reaction and distortion of halide leaving-group order

Author keywords

[No Author keywords available]

Indexed keywords

ACTIVATION ENERGY; ALKYLATION; CARCINOGENS; HYDROGEN BONDS; SOLVENTS; STOICHIOMETRY;

EID: 36849090582     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo702090p     Document Type: Article
Times cited : (33)

References (45)
  • 1
    • 0002696419 scopus 로고
    • Note that the chemistry literature contains a substantial number of citations with the German spelling Menschutkin, and also the English spelling Menshutkin
    • Menschutkin, N. Z. Phys. Chem. 1890, 6, 41-57. Note that the chemistry literature contains a substantial number of citations with the German spelling Menschutkin, and also the English spelling Menshutkin.
    • (1890) Z. Phys. Chem , vol.6 , pp. 41-57
    • Menschutkin, N.1
  • 5
    • 84986557922 scopus 로고
    • Streitwieser, A, Taft, R. W, Eds, Wiley: New York
    • Abraham, M. H. In Progress in Physical Organic Chemistry; Streitwieser, A., Taft, R. W., Eds.; Wiley: New York, 1974; Vol. 11, pp 1-87.
    • (1974) Progress in Physical Organic Chemistry , vol.11 , pp. 1-87
    • Abraham, M.H.1
  • 13
    • 36849040401 scopus 로고    scopus 로고
    • For examples of N-alkylation with methylene chloride, see: (a) Nevstad, G. O, Songstad, J. Acta Chem. Scand. B 1984, 38, 469-477
    • For examples of N-alkylation with methylene chloride, see: (a) Nevstad, G. O.; Songstad, J. Acta Chem. Scand. B 1984, 38, 469-477.
  • 17
    • 36849012928 scopus 로고    scopus 로고
    • The alkylation products with unsubstituted benzyl halides tended to precipitate very quickly during the reaction; therefore, the more soluble 4-tert-butylbenzyl halides were employed instead
    • The alkylation products with unsubstituted benzyl halides tended to precipitate very quickly during the reaction; therefore, the more soluble 4-tert-butylbenzyl halides were employed instead.
  • 18
    • 36849055955 scopus 로고    scopus 로고
    • N2 process, but with some of the organohalides we cannot rule out the possibility that the mechanism may involve two SET steps.
    • N2 process, but with some of the organohalides we cannot rule out the possibility that the mechanism may involve two SET steps.
  • 19
    • 36849000192 scopus 로고    scopus 로고
    • Another example of selective improvement of leaving-group ability in the order Cl > Br > I is the ratio k(1)/k(2). With 4-t-BuBn halides, the values of k(1)/k(2) are 4-t-BuBnCl (55), 4-t-BuBnBr (6.5), and 4-t-BuBnI (0.15). In other words, 4-t-BuBnCl reacts with macrocycle 1 much faster than with 2, whereas the ratio is reversed with 4-t-BuBnI.
    • Another example of selective improvement of leaving-group ability in the order Cl > Br > I is the ratio k(1)/k(2). With 4-t-BuBn halides, the values of k(1)/k(2) are 4-t-BuBnCl (55), 4-t-BuBnBr (6.5), and 4-t-BuBnI (0.15). In other words, 4-t-BuBnCl reacts with macrocycle 1 much faster than with 2, whereas the ratio is reversed with 4-t-BuBnI.
  • 20
    • 36849078751 scopus 로고    scopus 로고
    • The leaving-group ability of fluoride in SN2 reactions is about 200 times less than that of chloride, McMurry, J. Organic Chemistry; 6th ed, Thomson-Brooks/Cole: Belmont, CA, 2004, The main reason is the high strength of the C-F bond (e.g, bond strengths are CH3-F 108 kcal/mol, CH3-Cl 84 kcal/mol, CH3-Br 70 kcal/mol, and CH3-I 56 kcal/mol, t-BuBnF reacts with macrocycle 1 in CDCl3 with a rate constant of (5.63 ± 0.20) × 10 -5 M-1 s-1 at 298 K. In contrast, no reaction with 2 could be detected at 298 K. To provide a point of comparison, the experiments with t-BuBnF were repeated at 323 K, where k rel(1)/krel(2, 100, which means that the rate enhancement for fluoride leaving group is greater than that for chloride 100- vs 55-fold
    • rel(2) = 100, which means that the rate enhancement for fluoride leaving group is greater than that for chloride (100- vs 55-fold).
  • 22
    • 28544442086 scopus 로고    scopus 로고
    • Prereaction complexes can also be identified using non-steady state kinetic analysis. Parker, V. D. Pure Appl. Chem. 2005, 77, 1823-1833.
    • Prereaction complexes can also be identified using non-steady state kinetic analysis. Parker, V. D. Pure Appl. Chem. 2005, 77, 1823-1833.
  • 23
    • 36849052807 scopus 로고    scopus 로고
    • An X-ray crystal structure of 1 as its DMSO adduct (see the Supporting Information in ref 10) shows that the DMSO oxygen atom forms hydrogen bonds with the two NH residues in the macrocyclic cavity
    • An X-ray crystal structure of 1 as its DMSO adduct (see the Supporting Information in ref 10) shows that the DMSO oxygen atom forms hydrogen bonds with the two NH residues in the macrocyclic cavity.
  • 25
    • 0011083843 scopus 로고    scopus 로고
    • A similar but less dramatic correlation is seen when comparing leaving-group abilities for the Menschutkin reaction in aprotic and protic solvents. For example, moving from aprotic DMF to protic methanol enhances leaving-group ability in the order Cl > Br > I. Parker, A. J. Chem. Rev. 1969, 69, 1-32
    • A similar but less dramatic correlation is seen when comparing leaving-group abilities for the Menschutkin reaction in aprotic and protic solvents. For example, moving from aprotic DMF to protic methanol enhances leaving-group ability in the order Cl > Br > I. Parker, A. J. Chem. Rev. 1969, 69, 1-32.
  • 27
    • 36849014711 scopus 로고    scopus 로고
    • The transition state of a typical Menschutkin reaction at ambient temperature in moderately polar solvents is characterized by TΔS‡ values of -9 to -11 kcal/mol see ref 2, The highly negative ΔS‡ is attributed to ordering of the solvent cage and a negative of activation, which explains why the reaction is promoted by high pressure
    • The transition state of a typical Menschutkin reaction at ambient temperature in moderately polar solvents is characterized by TΔS‡ values of -9 to -11 kcal/mol (see ref 2). The highly negative ΔS‡ is attributed to ordering of the solvent cage and a negative volume of activation, which explains why the reaction is promoted by high pressure.
  • 28
    • 0037433269 scopus 로고    scopus 로고
    • Activation of a halide leaving group by hydrogen bonding is a strategy that is employed by the family of enzymes known as haloalkane dehydrogenases. The first catalytic step in the enzymatic process involves attack of an organohalide by an active-site carboxylate nucleophile, and a significant fraction of the rate enhancement is attributed to two NH residues in the enzyme active site that form stabilizing hydrogen bonds with the halide leaving group. Dev-Kesavan, L, Gao, J. J. Am. Chem. Soc. 2003, 125, 1532-1540
    • Activation of a halide leaving group by hydrogen bonding is a strategy that is employed by the family of enzymes known as haloalkane dehydrogenases. The first catalytic step in the enzymatic process involves attack of an organohalide by an active-site carboxylate nucleophile, and a significant fraction of the rate enhancement is attributed to two NH residues in the enzyme active site that form stabilizing hydrogen bonds with the halide leaving group. Dev-Kesavan, L.; Gao, J. J. Am. Chem. Soc. 2003, 125, 1532-1540.
  • 29
    • 36849019364 scopus 로고    scopus 로고
    • -1) as determined by NMR dilution experiments.
    • -1) as determined by NMR dilution experiments.
  • 30
    • 0037418209 scopus 로고    scopus 로고
    • For discussions of near attack conformation, see: a
    • For discussions of near attack conformation, see: (a) Hur, S.; Kahn, K.; Bruice, T. C. Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 2215-2219.
    • (2003) Proc. Natl. Acad. Sci. U.S.A , vol.100 , pp. 2215-2219
    • Hur, S.1    Kahn, K.2    Bruice, T.C.3
  • 41
    • 84890969654 scopus 로고    scopus 로고
    • Breslow, R, Ed, Wiley: New York
    • (a) Artificial Enzymes; Breslow, R., Ed.; Wiley: New York, 2005.
    • (2005) Artificial Enzymes


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.