Reversible Generation of Labile Secondary Carbocations from Alcohols in the Nanospace of H-Mordenite and Their Long-Lasting Preservation at Ambient Temperature
作者:Yoichi Masui、Taiki Hattori、Makoto Onaka
DOI:10.1021/jacs.7b03336
日期:2017.6.28
side reactions prevailed in TfOH and formation of 2 was not observed. Preservation of other secondary carbocations from benzhydrol, 4,4′-dichlorobenzhydrol, and 9-fluorenol was also realized in H-Mor. It was confirmed that the generation of 2 from 1 was controlled by thermodynamic equilibrium rather than kinetic regulations. The equilibrium between 2 and 1 was accompanied by reversible chromism, which
由于不稳定,因此在环境温度下很难长时间观察到次级碳正离子。在这项研究中,当4,4'-二氟苯甲酸(1)与H-丝光沸石(H-Mor)混合时,产生了4,4'-二氟二苯甲基阳离子(2)作为主要产物,通过UV-vis和13 C-MAS NMR光谱学分析,在室温下保存1周以上。令人惊讶地,1的聚合和歧化在H-Mor的微孔中几乎没有进行。但是,这些副反应主要存在于TfOH和2的形成中。没有被观察到。在H-Mor中,还实现了从苯甲醇,4,4'-二氯苯甲醇和9-芴醇中保留其他次级碳正离子的作用。可以确定,从1生成2是受热力学平衡而不是动力学规则控制的。2和1之间的平衡伴随着可逆的色度,通过改变H-Mor中的水分含量可以很容易地控制色度。此外,本文描述了在微孔内表面上密集地填充有酸位的沸石中的特定酸催化的新见解。