Concepts of sterically hindered resonance and buttressing effect: gas-phase acidities of methyl-substituted benzoic acids and basicities of their methyl esters
Concepts of sterically hindered resonance and buttressing effect: gas-phase acidities of methyl-substituted benzoic acids and basicities of their methyl esters
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位阻共振和支撑效应的概念：甲基取代苯甲酸的气相酸性及其甲酯的碱性
DOI：
10.1021/ja00078a052
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
P. Maria
中科院分区：
文献类型：
--
作者：
M. Decouzon;P. Ertl;O. Exner;J. Gal;P. Maria
两个经典术语«共振位阻»和«支撑效应»在九甲基取代苯甲酸的气相酸度及其甲酯的气相碱度的基础上重新审视，使用FT-ICR光谱测量。通过将这些数据与已发表的中性物的生成热相结合，并利用等测反应原理，分别对酸分子、它们的阴离子（去质子化）和它们的质子化阳离子（被相应的甲酯的质子化形式所取代）的相对生成焓进行了评估。所有物种的能量也在半经验水平上计算（AM1）。
Two classical terms «Steric Hindrance to Resonance» and «Buttressing Effect» are revisited on the basis of the gas-phase acidities of nine methyl-substituted benzoic acids and of the gas-phase basicities of their methyl esters, measured using FT-ICR spectrometry. By combining these data with published heats of formation of the neutrals and by using the principle of isodesmic reactions, relative enthalpies of formation were evaluated separately for the acid molecules, their anions (deprotonated), and their protonated cations (substituted by the protonated forms of the corresponding methyl esters). Energies of all species were also calculated at the semiempirical level (AM1)