全氟烷基磺酸酯C—O键断裂的同面S_N2反应  

Front-Side S_N2 Reaction, CF_3SO_3CF_2CF_3+F^-, Leading to the C—O Cleavage

作　　者：郭丽[1] 虞忠衡[1] 朱士正[2] 陈庆云[2] 

机构地区：[1]中国科学院化学研究所分子动态和稳态国家重点实验室,北京100080 [2]中国科学院上海有机化学研究所,上海200032

出　　处：《化学学报》2005年第10期897-902,i002,共7页Acta Chimica Sinica

基　　金：国家自然科学基金(Nos.20276023;20032010and20472088)资助项目.

摘　　要：用密度泛函理论研究了CF3SO3CF2CF3+F-的碳氧键断裂反应的机理.首先,用DFT方法优化了反应物、中间体、过渡态、产物的平衡构型,分析了碳氧键断裂反应的势能面变化.发现在SN2反应机理中,除了S—O断裂SN2反应外,引起C—O键断裂的同面进攻也是一个可能的反应途径.理论计算表明,最终反应的产物是受热力学控制的,S—O键的断裂绝对地优于C—O的断裂.因此,C—O断裂的同面机理虽然是可能的,但却难以被实验观察到.本文还讨论了端基—CF3在同面SN2反应中的邻位效应,以及基组对这个效应的影响.The front-side S(N)2 reaction, CF3SO3CF2CF3+F- leading to the C-O cleavage was studied using DFT. The reactant complex, transition state, product complex and products, including their vibration frequencies, were optimized and calculated at B3LYP/6-311G** level. The potential energy surface for the front-side S(N)2 reaction was investigated, showing that the front-side S(N)2 mechanism is possible. However, as shown by computation, the products are thermodynamically controlled, and the S-O cleavage is predominates over the C-O cleavage. As a result, it is difficult for the products resulting from the C-O cleavage to be detected experimentally. Meanwhile, the neighboring effect of the -CF3 group on the front-side S(N)2 mechanism was found.

关 键 词：SN2反应 键断裂 全氟烷基 磺酸酯 DFT方法 热力学控制 理论研究 密度泛函 平衡构型 反应机理 反应途径 实验观察 邻位效应 反应物 中间体 过渡态 势能面 计算表 产物 端基 碳 

分 类 号：O621.13[理学—有机化学]