【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.更多还原

【Abstract】 The front-side SN2 reaction, CF3SO3CF2CF3+F - , leading to the C—O cleavage was studied us- ing 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 SN2 reaction was investigated, showing that the front-side SN2 mechanism is possible. However, as shown by computation, the products are thermodynamically controlled, and the S—O cleavage is pre- dominates 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 SN2 mechanism was found.更多还原