质子化
化学
取代基
分子
价(化学)
计算化学
单独一对
结晶学
亲核细胞
质子亲和力
立体化学
离子
有机化学
催化作用
作者
Tom Slee,R. F. W. Bader
出处
期刊:Journal of Molecular Structure-theochem
[Elsevier]
日期:1992-03-01
卷期号:255: 173-188
被引量:19
标识
DOI:10.1016/0166-1280(92)85009-a
摘要
The calculated electron distributions of simple carbonyl compounds (XCHO) and their conjugate acids are described in terms of the theory of atoms in molecules. This allows the factors affecting the protonation energies of carbonyl compounds to be discussed in terms of well-defined properties of the electron density. Both substituent electropositivity and π-donation ability are shown to favour large protonation energies. The net effect of these two factors on the stabilisation of positive charge in the product shows up in the charge on the "proton" and in the related position of the O-H bond critical point, both of which correlate well with the protonation energy. The Laplacian of the electron distribution was also calculated. It is shown that the preferred orientation (cis or trans) of the proton with respect to the substituent is generally indicated by the relative magnitude of the maxima in the valence-shell charge concentration (VSCC) that are present at the positions of the "lone-pairs" of the oxygen atom. Minima within the VSCC occur above and below the carbonyl atom of both neutral and protonated species, the position of which indicates the optimum angle of nucleophilic attack.
科研通智能强力驱动
Strongly Powered by AbleSci AI