文献类型：期刊文献

英文题名：Solvent Effects on the Symmetric and Asymmetric SN2 Reactions in the Acetonitrile Solution: A Reaction Density Functional Theory Study

作者：Tang, Weiqiang[1,2];Zhao, Jihao[1,2];Jiang, Peng[1,2,5];Xu, Xiaofei[1,2];Zhao, Shuangliang[1,2,3,4];Tong, Zhangfa[3,4]

机构：[1]East China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Sch Chem Engn, Shanghai 200237, Peoples R China;[3]Guangxi Univ, Guangxi Key Lab Petrochem Resource Proc & Proc In, Nanning 530004, Peoples R China;[4]Guangxi Univ, Sch Chem & Chem Engn, Nanning 530004, Peoples R China;[5]Wuhan Inst Technol, Sch Chem Engn & Pharm, Key Lab Green Chem Proc, Minist Educ, Wuhan 430073, Peoples R China

年份：2020

卷号：124

期号：15

起止页码：3114

外文期刊名：JOURNAL OF PHYSICAL CHEMISTRY B

收录：;EI(收录号：20202208758340);WOS:【SCI-EXPANDED(收录号:WOS:000526368900015)】；

基金：This work is supported by the National Natural Science Foundation of China (Nos. 21878078, 21978079, and 91934302), the National Natural Science Foundation of China for Innovative Research Groups (No. 51621002), and the 111 Project of China (No. B08021).

语种：英文

外文关键词：Free energy - Intelligent systems - Organic solvents - Solvation - Acetonitrile - Energy barriers - Polarization - Monte Carlo methods

摘要：Bimolecular nucleophilic substitution (S(N)2) reactions are of great importance in chemistry and biochemistry due to their capability of constructing functional groups. In this work, we investigate the solvent effect on the free energy profiles of symmetric and asymmetric S(N)2 reactions in the acetonitrile solution using the proposed reaction density functional theory (RxDFT) method. This multiscale method utilizes quantum density functional theory for calculating intrinsic reaction free energy coupled with classical density functional theory for addressing solvation contribution. We find that the presence of acetonitrile brings both the polarization effect and solvation effect on the reaction pathways. For the eight selected symmetric S(N)2 reactions, the predicated reaction pathways agree well with the results from the direct and thermodynamic cycle (TC) methods with the SMD-M062X solvation model. In addition, the polarization effect reduces the free energy barriers by about 6 kcal/mol, while the solvation effect increases the barriers by about 18 kcal/mol. For the four selected asymmetric S(N)2 reactions, the predicted reaction pathways agree well with the results from the Monte Carlo simulations and experiments. The polarization effect and the solvation effect mutually reduce the free energy barriers, and the solvation effect plays a dominant role.