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Volumn 125, Issue 8, 2003, Pages 2142-2147

Are the enolates of amides and esters stabilized by electrostatics?

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PROTONATION;

EID: 0037467147     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja029102a     Document Type: Article
Times cited : (37)

References (46)
  • 6
    • 0013447104 scopus 로고    scopus 로고
    • note
    • In this perspective, the electron density previously shared by the oxygen and the proton is viewed as now residing purely on oxygen, thereby increasing the negative charge on oxygen. Electrostatic stabilization results from the interaction of this increased negative charge with the electron density distribution of the remainder of the molecule, which is viewed as remaining unchanged.
  • 8
    • 0013453728 scopus 로고    scopus 로고
    • note
    • In this way of thinking, the interaction between the "ordinary" partial charges on atoms bonded to each other is ignored, however, since it is assumed to be part of the normal bond energy.
  • 9
    • 0013436372 scopus 로고    scopus 로고
    • note
    • The two definitions of the electrostatic effect might at first appear completely different, but in fact they are quite similar. The definition of the electrostatic effect described here corresponds to the energy associated with adding or removing a proton and leaving both the geometry and the electron density distribution of the remainder of the molecule unchanged, with only one minor exception: the atom actually experiencing protonation or deprotonation is viewed as undergoing a localized relaxation of its electron density distribution. That is, in a deprotonation, the electrons originally in the X-H bond are assumed to relax into a lone pair on X (in analogy to the traditional arrow-pushing of electrons by organic chemists). The physical chemist's definition and the organic chemist's definition of the electrostatic contribution are consequently not so different as they at first appear.
  • 10
    • 0000010481 scopus 로고    scopus 로고
    • For a discussion of inductive and electrostatic effects, and transmission through bonds and through space, see (a) Exner, O. J. Phys. Org. Chem. 1999, 12, 265-274. (b) Charton, M. J. Phys. Org. Chem. 1999, 12, 275-282.
    • (1999) J. Phys. Org. Chem. , vol.12 , pp. 265-274
    • Exner, O.1
  • 11
    • 0000351903 scopus 로고    scopus 로고
    • For a discussion of inductive and electrostatic effects, and transmission through bonds and through space, see (a) Exner, O. J. Phys. Org. Chem. 1999, 12, 265-274. (b) Charton, M. J. Phys. Org. Chem. 1999, 12, 275-282.
    • (1999) J. Phys. Org. Chem. , vol.12 , pp. 275-282
    • Charton, M.1
  • 12
    • 0033958872 scopus 로고    scopus 로고
    • and references therein
    • Rablen, P. R. J. Am. Chem. Soc. 2000, 122, 357-368 and references therein.
    • (2000) J. Am. Chem. Soc. , vol.122 , pp. 357-368
    • Rablen, P.R.1
  • 20
    • 0003922511 scopus 로고    scopus 로고
    • Prentice Hall: Englewood Cliffs, NJ
    • Bruice, P. Y. Organic Chemistry; Prentice Hall: Englewood Cliffs, NJ, 2001; p 829.
    • (2001) Organic Chemistry , pp. 829
    • Bruice, P.Y.1
  • 26
    • 0013440908 scopus 로고    scopus 로고
    • note
    • The calculated energy for reaction 3.1 might fall outside the experimental range, depending on the assessment one makes of the experimental uncertainty. However, another source of discrepancy between the calculated and experimental values is that the calculated values correspond to zero Kelvin, while the experimental values are for higher temperatures.
  • 35
    • 0013440910 scopus 로고    scopus 로고
    • note
    • In cases where the HF/3-21G* energies of one or more rotamers were similar, HF/6-31G* optimizations were used to verify which conformer was of lowest energy.
  • 36
    • 0013403616 scopus 로고    scopus 로고
    • note
    • There were two minor exceptions: at the B3LYP/6-31+G** level only, acetone and the enolate anion of Z-methyl acetate each had one imaginary frequency in a planar, Cs symmetric geometry. However, magnitudes of these frequencies were so small that the planar structures were used anyway.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.