Electronic and Steric Effects: How Do They Work in Ionic Liquids? The Case of Benzoic Acid Dissociation
作者:Francesca D’Anna、Salvatore Marullo、Paola Vitale、Renato Noto
DOI:10.1021/jo100914p
日期:2010.7.16
to have a measure of the importance of the steric effect of the substituents both para- and ortho-substituted benzoic acids were analyzed. The probe reaction was studied in two ionic liquids differing for the ability of the cation to give hydrogen bond and π−π interactions, namely [bm2im][NTf2] and [bmpyrr][NTf2]. Data collected show that benzoic acids are less dissociated in ionic liquid than in water
需要测量离子液体溶液中某些取代的苯甲酸的强度,导致我们使用对硝基苯酚钠的质子平衡作为探针反应,该方法通过在298 K下分光光度滴定法进行了研究。为了评估存在于芳环上的取代基的电子效应的重要性,同时考虑了吸电子和-给体取代基。此外,为了测量取代基的空间效应的重要性,分析了对位和邻位取代的苯甲酸。在两种离子液体中研究了探针反应,两种离子液体的阳离子给出氢键和π-π相互作用的能力不同,即[bm 2 im] [NTf 2 ]和[bmpyrr] [NTf2 ]。收集的数据表明,苯甲酸在离子液体中的离解比在水溶液中要少。此外,平衡常数值似乎受到离子液体阳离子的性质和酸的结构的显着影响。特别是,在水和芳族离子液体中,邻位立体效应似乎有不同的作用,从而确定了该溶剂介质中邻位取代的苯甲酸的特殊行为。