超酸POSA催化酯化反应动力学及线性自由能关系  

RESEARCH ON KINETICS AND LFE RELATIONSHIP OF SUPERACID POSA CATALYZED ESTERIFICATION

作　　者：贺明谦 傅相锴[1] 

机构地区：[1]西南师范大学化学系

出　　处：《物理化学学报》1990年第6期739-742,共4页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金

摘　　要：全氟辛基磷酸(C_8F_(17)SO_3H,Perfluorooctanesulfonic acid,POSA)是熔点为90℃的固体超酸.我们首次测得其酸度函数值是-12.11±0.03,并将其用于催化Friedel-Crafts烃基化反应和醇脱水制烯,取得了良好的结果.本文报导我们研究POSA催化酯化反应的动力学和线性自由能关系. 线性自由能关系是研究反应动力学微观过程的有效方法之一.对反应速度常数、平衡常数的测定,对于活化参数△E、△S、△H的计算以及反应机理的深入了解都是非常有用的.近年报导的Wittig反应线性自由能关系的研究即是一例. 我们测定了POSA催化对位取代苯甲酸的乙酯化反应的速率常数k。From superacid POSA (perfluorooctanesulfonic acid) catalyzed esterification ofp-substituted benzoic acids with ethanol, we got not only the rate canstants k, theenergy of activation ΔE, the entropy of activation ΔS~?, and the enthalpy of acti-vation ΔH~?; but also a good Hammett linear Free energy relationship (LFE Rela-tionship). This is the first report of applying LFE relationship to superacid catalysis.Finally, the reaction intermediate, the reaction constant p, and the mechanism ofthe reaction were also discussed. It is deduced by this paper that the mechanism ofPOSA catalyzed esterification is basically identical with those of normal strong acidscatalysis, and the reaction is a process of general acid catalysis.

关 键 词：超酸 PSOA 酯化反应 动力学 

分 类 号：TQ426.94[化学工程]