Gas-Phase and Solution Basicities of Some Alkyl 2,6-Dialkylphenyl Ketones: a Comparative Analysis
作者:Carlo Dell'Erba、Michelangelo Gruttadauria、Angelo Mugnoli、Renato Noto、Marino Novi、Giorgio Occhiucci、Giovanni Petrillo、Domenico Spinelli
DOI:10.1016/s0040-4020(00)00370-7
日期:2000.6
result of a compensation of steric and electronic effects associated with the bulkiness and to the polarizability, respectively, of R and/or R′. On the contrary, the basicity in concentrated sulfuric acid undergoes, along the same series of compounds, a variation of nearly 8 pK units, as a consequence of steric inhibition of solvation of the protonated carbonyl as the main effect played by R and/or R′.
由于补偿了空间和自由基,已发现许多烷基2,6-二烷基苯基酮(2,6-R 2 C 6 H 3 COR')的气相碱性几乎对结构变化不敏感。分别与R和/或R'的体积和极化率相关的电子效应。相反,在相同系列的化合物中,浓硫酸中的碱度变化接近8 p K由于R和/或R'所起的主要作用,是由于空间抑制质子化羰基的溶剂化而产生的。缩合阶段的结果与有关一些4-取代的2,6-二甲基苯乙酮和4-取代的苯乙酮的最新发现以及大量二烷基或烷基芳基酮的数据非常吻合(无论是从文献还是从得出整体p K BH +与m ∗的相关性(斜率= 8.8,n = 31,r= 0.996; 等式 (3)似乎具有普遍意义,并且至少在不存在强共轭相互作用的情况下,确定了对溶剂化的空间抑制作用是影响羰基碱度的常见因素。