alpha-Effect in SN2 reactions revisited: Do alpha-nucleophiles accelerate SN2 reactions?

DOI

Bibliographic Information

Other Title
  • SN2反応におけるα効果の再考：α求核種は本当に反応を加速するか

Description

In order to clarify the origin of the alfa-effect in SN2 reactions at saturated carbon centers, 28 gas-phase reactions have been examined computationally by using the high level G2(+) method. The reactions include: Nu- + CH3X -> CH3Nu + X- [X = F and Cl; Nu- = HO-, HS-, CH3O-, Cl-, Br-, HOO-, HSO-, FO-, ClO-, BrO-, NH2O-, and HC(=O)OO-]. It was found that all alfa-nucleophiles examined exhibit downward deviations from the correlation line between the overall barriers and proton affinities for normal nucleophiles, indicating the existence of the alfa-effect in the gas phase. The transition state (TS) for the alfa-nucleophiles are characterized by less advanced C-X bond cleavages than the normal nucleophiles, leading to smaller deformation energies and overall barriers. The size of the alfa-effect is related to the electron density on the alfa-atom, and increases when the position of alfa-atom is changed from left to right and from bottom to top in the periodic table.

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Details 詳細情報について

  • CRID
    1390282680532059264
  • NII Article ID
    130004645144
  • DOI
    10.11494/kisoyuki.18.0.47.0
  • Text Lang
    ja
  • Data Source
    • JaLC
    • CiNii Articles
  • Abstract License Flag
    Disallowed

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