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| 1 | 取代基效应定量研究新进展显示文摘综述了最近20多年有机化学取代基效应定量研究所取得的诸多新进展.主要内容包括:(1)电负性均衡原理得到普遍认同并用于计算分子中电荷分布和基团的诱导效应,分子电负性计算方法在几何平均法、调和平均法、加权平均法的基础上又提出了价电子均衡方法,进一步扩展了电负性均衡原理的应用范围.(2)试剂亲电、亲核能力的实验测定,提出了以二苯甲基正离子和醌甲基化合物等作为参考化合物的标定方法,其研究范围被扩展到气相条件、有机金属反应和自由基体系,得到一系列试剂的亲核参数N和亲电参数E.理论上提出亲电性指数和亲核性指数的概念及其定量计算公式,并对实验测定参数和理论计算指数之间的关系进行了深入研究.(3)极化效应参数从最初的经验方法,进而采用量子化学方法计算,再用统计方法提出了烷基极化效应指数PEI和基团极化效应参数PEIX,被广泛用于解释和估算有机化合物的气相酸碱性、电离能、生成焓、键能、反应速率、水溶解性和色谱保留值.(4)直接由取代苯的紫外光谱吸收能量计算得到的取代基激发态参数exCC,不同于取代基在分子处于基态的极性参数和自由基状态下的自旋离域效应参数,该参数用于对位二取代苯、取代二苯乙烯、二取代氮苄叉苯胺等多类有机化合物紫外光谱的定量相关,结果良好.(5)立体屏蔽效应的提出区分了传统的三种立体效应.在羰基与亲核试剂加成反应立体选择性定量表示,提出了立体选择性指数Ci;在表示基团对反应中心表面积屏蔽的定量提出了屏蔽参数SR,进一步基于反应中心体积被屏蔽的角度提出了拓扑立体效应指数TSEI,这些参数在分子内二面角、反应的立体选择性、烯烃和烷基苯的生成焓、咪唑离子液体的酸性以及烷烃与羟基自由基的反应速率等方面得到良好的应用.此外,论文还对有机化学取代基效应定量研究中值得进一步深入探索的领域和问题提出了建议和展望. | 曹晨忠 武亚新 | 2013 | 中国科学:化学2013，43，7： | 6 |
| 2 | Recent progress in quantifying substituent effects显示文摘This paper summarizes significant progress in quantifying organic substituent effects in the last 20 years. The main content is as follows: (1) The principle of electronegativity equalization has gained wide acceptance, and has been used to calculate the intramolecular charge distribution and inductive effect of groups. A valence electrons equalization method was proposed to compute the molecular electronegativity on the basis of geometric mean method, harmonic mean method, and weighted mean method. This new calculation method further extended the application of the principle of electronegativity equalization. (2) A scale method was established for experimentally determining the electrophilic and nucleophilic ability of reagents, in which benzhydryliumions and quinone methides were taken as the reference compounds, and the research field was extended to the gas phase conditions, organometallic reaction and radicals system. Moreover, the nucleophilicity parameters N and electrophilicity parameters E for a series of reagents were obtained. The definition and quantitative expression of electrophilicity index and nucleophilicity index were proposed theoretically, and the correlation between the parameters from experimental determination and the indexes from theoretical calculation was also investigated. (3) The polarizability effect parameter was initially calculated by empirical method and further developed by quantum chemistry method. Recently, the polarizability effect index of alkyl (PEI) and groups (PEI X ) were proposed by statistical method, and got wide applications in explaining and estimating gas-phase acidity and basicity, ionization energy, enthalpy of formation, bond energy, reaction rate, water solubility and chromatographic retention for organic compounds. (4) The excited-state substituent constant ex CC obtained directly from the UV absorption energy data of substituted benzenes, is different from the polar constants in molecular ground state and the radical spin-delocalization effects constants in molecular radical state. The proposed constant ex CC correlated well with the UV absorption energy of many kinds of organic compounds, such as 1,4-disubstituted benzenes, substituted stilbenes, and disubstituted N-benzylidenebenzenamine. (5) The establishment of the steric shielding effect distinguished the three traditional steric effects. The stereoselectivity index C i was proposed to quantify the stereoselectivity of the addition reaction of carbonyl with nucleophilic reagent. The shielding parameter S R was defined to quantitatively express the specific surface of the reaction center screened by a group. Further, the Topological Steric Effect Index (TSEI) of a group was proposed on the basis of the relative specific volume of reaction center screened by the atoms of substituents. These parameters can be applied in estimating the intramolecular dihedral angles, stereoselectivity of reaction, enthalpies of formation of alkenes and alkylbenzene, acidity of substitutedimidazolium ionic liquid, and the reaction rate of alkane and hydroxyl radical. In addition, some suggestions and prospects for further studies on quantifying the organic substituent effects were presented in this paper. | CAO ChenZhong WU YaXin | 2013 | Science China Chemistry2013，56，7： | 4 |
| 3 | 单取代烷烃生成焓与键能之间的定量关系显示文摘单取代烷烃生成焓的定量估算式与键能的定量估算式中存在相同的电子效应参数,可推断出把电子效应参数作为桥梁,找出单取代烷烃生成焓与其键能之间的定量关系,建立利用生成焓值来确定其键能的新方法.本文用74个单取代烷烃的生成焓ΔfHθ(R—X)结合BDE(X—Me)、NC、h[X]、PEI(R)和ΔPEI(R)对其键能BDE(X─R)实验值进行回归分析,所得回归方程有良好的相关性,相关系数达0.999 9,实验值与计算值之间的平均绝对误差仅3.47 k J,落在实验误差范围内.进而用留一法对其稳定性和预测能力进行验证(R_(CV)=0.999 9),结果表明利用单取代烷烃生成焓建立的键能估算模型是合理并且有效的.本文将看上去相差甚远的两种物理化学性能(键能和生成焓)从理论上探索了它们之间的内在联系,为从同一分子结构基础上理解不同性能之间的联系提供了新的视角和方法. | 武亚新 于方彩 | 2017 | 南华大学学报(自然科学版)2017，31，4： | 0 |
| 4 | Theoretical estimation of Hammett σ_p constants of organic radical groups显示文摘A quantum chemistry method was developed to calculate the Hammett substituent constants of various organic radicals. These newly obtained constants allow,for the first time,the quantitative analysis of the electron demand of organic radicals. Calcula-tions reveal that the electron demand of organic radicals varies dramatically. It was demonstrated that the Hammett relationship of bond dissociation energies is determined only by the change of electron demand during the homolysis process. | WANG Chen FU Yao LIU Lei | 2010 | Chinese Science Bulletin2010，55，25： | 0 |
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