Is There a Minimum Electrophilicity Principle in Chemical Reactions？

For 25 simple reactions, the changes of the hardness （△η）, polarizability （△α） and electrophilicity index （△ω） and their cube-roots （△η^1/3, △α^1/3, △ω^1/3） were calculated. It is shown that although the Maximum Hardness and Minimum Polarizability Principles are not valid for all reactions, but in most cases △ω^1/3〈0, whereas we always find △ω〈0. Our observation implies to this fact that for those chemical reactions in which the number of moles decreases or at least remains constant, the most stable species （reactants or products） have the lowest sum of electrophilicities. In other words ＂the natural direction of a chemical reaction is toward a state of minimum electrophilicity＂. This fact may be called Minimum Electrophilicity Principle （MEP）.     

Ab initio calculation of molar volumes: Comparison with experiment and use in solvation models

A simple and efficient procedure of calculating molecular volume (V_M) based on the Monte Carlo method is presented. The volume of a molecule is defined by the volume occupied by the 0.001-au electron density envelope. We have employed this method to compute the molecular volumes (V_M) of a large selection of organic molecules and compare them with the corresponding molar volumes (V_m) measured in the liquid state. A strong correlation is found to exist between the V_M and V_m values (V_M/V_m ≈ 0.75). Using this linear relationship, the calculated molecular volume may provide an estimate of the cavity-volume parameter in solvent-effect calculations. As a chemical application of molecular volume, we have investigated the conformational equilibrium of 1,2-difluoroethane in the liquid state using the self-consistent reaction field theory. © 1995 by John Wiley & Sons, Inc.     

重氮苯与不同亲核试剂结合选择性:共价与非共价作用分析

重氮苯与亲核试剂的作用方式及其反应机理一直未能被完全阐明. 基于密度泛函理论, 本文计算了 6种亲核试剂与重氮苯结合时的结合位点及反应过程中的反应坐标. 计算结果表明, 化学硬度可以作为预测不同亲核试剂与重氮苯结合位点的主要描述符. 基于复合物体系范德华表面的平均局域离子化能等参数, 还提出了可以定量预测重氮苯与亲核试剂结合反应活化能垒的描述符. 这些理论研究结果对理解重氮苯与亲核试剂的反应机制、 寻找更优反应条件具有重要意义.     

Volumetric behavior and micelle formation of aqueous surfactant mixtures

A thermodynamic treatment of the volumetric behavior of surfactant mixtures in water have been developed on the basis of the thermodynamic treatment of mixed micelle by Motomura et al. Densities of aqueous solutions of mixtures of decyltrimethylammonium bromide (DeTAB) and dodecyltrimethylammonium bromide (DTAB) have been measured as a function of total molality at constant compositions. The apparent molar volumes of the mixtures have been derived from the density data and the mean partial molar volume of monomeric surfactant mixture V _t ^w , the molar volume of mixed micelle V^M/N _t ^M , the voluem of formation of mixed micelle _W ^M V, and the composition of surfactant in the mixed micelle have been evaluated. The V _t ^W , V^M/N _t ^M , and _W ^M V have been observed to depend on the composition. The linear dependence of V _t ^W and V^M/N _t ^M on the composition indicates that the mixing of DeTAB and DTAB is ideal both in the monomeric and micellar states. This has been confirmed further by the shape of the critical micelle concentration vs. composition curves.     

用量子化学参数研究烯烃聚合物定量构效关系

以密度泛函理论(DFT)方法所得的烯烃聚合物结构单元的物性参数如总能量E_t、内能E_in、等容比热C_V、熵S、四极矩Q_ii、偶极矩 µ、平均极化率α及原子最大负电荷q^－等8个量子化学参数, 用逐步回归法分别建立了这些参数与摩尔体积V_{298 K}, 摩尔等张体积P_s、摩尔吸收常数色散分量F_d、摩尔折射率R_LL、摩尔抗磁磁化率χ、摩尔粘度温度函数H_vsum、摩尔Rao函数U_R及摩尔Hartmann函数U_H的结构-性能定量关系 (QSPR) 模型, 其测试集的决定系数R²分别是: V_{298 K} 为0.989, P_s为0.982, F_d为0.975, R_LL为0.997, χ为0.988, H_vsum为0.914, U_R为0.988及U_H为0.972. 结果表明, 用这些量子化学参数所建立的聚合物QSPR模型能用于聚合物性能的预测.     

Charge‐discharge properties of composites of polypyrrole and vanadium oxide powder

Composite of polypyrrole and crystalline V₂O₅ powder was prepared by chemical oxidation of pyrrole with use of V₂O₅ powder itself as an oxidizing agent. The V₂O₅ content was changed from 0 to 94 wt% by changing the amount of V₂O₅ dispersed in the preparation bath. The pellet electrodes could be prepared by pressing the composite powder alone even if amount of polypyrrole in the composite was only 6 wt%. The resulting pellet electrode exhibited good charge‐discharge performance as a positive electrode of Li rechargeable battery in an electrolyte solution as well as in a quasi‐solid cell fabricated by using a gel electrolyte sheet of poly(methyl methacrylate).