F~- + NH_2Cl反应体系的理论研究:以氮原子为中心的亲核取代反应
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- 英文论文题名：Comprehensive Theoretical Studies on F~-+ NH_2Cl Reaction:Nucleophilic Substitution at Neutral Nitrogen
- 论文作者：刘旭 ; 杨丽 ; 张家旭
- 英文论文作者：Xu Liu ; Li Yang ; Jiaxu Zhang ; School of Chemistry and Chemical Engineering ; Harbin Institute of Technology
- 年：2016
- 作者机构：哈尔滨工业大学化工与化学学院;
- 论文关键词：势能曲线 ; 氮中心亲核取代反应 ; 电子结构理论
- 会议召开时间：2016-07-01
- 会议录名称：中国化学会第30届学术年会摘要集-第四十四分会：化学动力学
- 语种：中文
- 分类号：O621.25
- 学会代码：ZGHY
- 会议名称：中国化学会第30届学术年会-第四十四分会 ; 化学动力学
- 会议地点：中国辽宁大连
- 主办单位：中国化学会
- 学会名称：中国化学会
- 页数：1
- 文件大小：328k
- 原文格式：D
- 会议级别：全国
摘要
尽管以氮原子为中心的S_N2亲核取代反应(S_N2@N)在有机合成和致癌方面发挥着重要的作用~([1,2]),但对其相关研究仍相对较少。本文应用广泛的电子结构理论研究了S_N2@N的模型反应─NH_2Cl+F~-体系。该体系的势能曲线展示了与碳中心体系(S_N2@C)相似的"双势阱"模型。分别发现了低能垒、占主导地位的后进攻S_N2通道(back-side S_N2),能量较高的前进攻S_N2通道(front-side S_N2)和质子转移通道(PT)。对比S_N2@C结果,S_N2@N体系的反应势垒两侧形成C1对称性的氢键化合物NH——X(X=F、Cl),而S_N2@C体系会形成对称性较高的离子偶极化合物;另外,NH_2Cl+F~-体系的质子转移通路也要比F~-+CH_3Cl体系竞争力强。计算表明,不同的理论方法对F~-+NH_2Cl体系的势能面性质会有较小的影响。对于主要的back-side S_N2通道,MP2、CAM-B3LYP、M06-2X和MPW1K方法更好的符合高精度的CCSD(T)/CBS计算结果,推荐用于直接动力学模拟,揭示以氮原子为中心的S_N2反应的微观机理和动力学行为规律。
The potential energy profile for the S_N2@N of chloramine(NH_2Cl) with fluorine anion(F~-) has been characterized by extensive electronic structure calculations. The back-side S_N2 channel dominates the reaction with the front-side S_N2 channel becoming feasible at higher energies. The minimum energy pathway shows a resemblance to the double-well potential model for S_N2 reactions at carbon. In the F~-+ NH_2Cl system, the proton transfer pathway is found to become more competitive with the S_N2 pathway than in the F~-+ CH_3Cl system. The MP2 and CAM-B3LYP, as well as M06-2X and MPW1K functionals are recommended for the direct dynamics simulations.
The potential energy profile for the S_N2@N of chloramine(NH_2Cl) with fluorine anion(F~-) has been characterized by extensive electronic structure calculations. The back-side S_N2 channel dominates the reaction with the front-side S_N2 channel becoming feasible at higher energies. The minimum energy pathway shows a resemblance to the double-well potential model for S_N2 reactions at carbon. In the F~-+ NH_2Cl system, the proton transfer pathway is found to become more competitive with the S_N2 pathway than in the F~-+ CH_3Cl system. The MP2 and CAM-B3LYP, as well as M06-2X and MPW1K functionals are recommended for the direct dynamics simulations.
引文
[1]Ulbrich,R.;Famulok,M.;Bosold,F.;Boche,G.Tetrahedron Lett.1990,31,1689.
[2].Helmick,J.S.;Martin,K.A.;Heinrich,J.L.;Novak,M.J.Am.Chem.Soc.1991,113,3459.
[2].Helmick,J.S.;Martin,K.A.;Heinrich,J.L.;Novak,M.J.Am.Chem.Soc.1991,113,3459.