用计算化学法探讨(Cl^-+CH_3Br→CH_3Cl+Br^-)S_N2亲核取代反应的溶剂效应

A Computational Method for Solvent Effects on the (Cl^-+CH_3Br→CH_3Cl+Br^-)S_N2 Nucleophilic Substitution Reaction

本研究采用GAUSSIAN03 HF/6-31+G(d)计算方法讨论(Cl-+CH3Br→CH3Cl+Br-)SN2亲核取代反应在6种不同极性溶剂中的反应速率。溶剂分为极性和非极性两类。分别采用过渡态理论和SN2亲核取代反应溶剂效应理论,分别计算反应速率常数并加以对比,判断反应进行难易程度。计算中考虑了反应温度273.15K,1atm(标准状态)情况。还计算了标准状态下反应平衡常数,同时验证了由反应速率计算得出的结论。计算过程中采用GaussView 4.1搭建分子模型。

In this research, a computational method GAUSSIAN03 at HF/6-31＋G（d） （basis set） level was applied to evaluate reaction rates of （Cl-＋CH3Br→CH3Cl＋Br-） SN2 nucleophilic substitution reaction in six solvents which are classifi ed into two categories of polar and nonpolar reagent. Reaction rate constants were calculated with transition state theory and formula of reaction rate constant for solvent effects on SN2 reaction. Comparison of them was obtained. The feasibility of each SN2 reaction in six solvents was evaluated. Reaction temperature at 273.15K and 1 atm were taken in the calculations. Standard equilibrium constants were obtained and used to verify conclusion drawn from the calculations on reaction rate constants. GaussView 4.1 was applied to build molecular structures.