采用电位滴定法在DMSO／H2O混合溶剂体系中测定磺酰脲（ …

采用电位滴定法在ＤＭＳＯ／Ｈ２Ｏ（质量比８０：２０）混合体系中测定了横酰脲和三唑并嘧啶磺酰胺类除草剂的酸离解常数,进而采用回归分析方法探讨了测得的ｐＫ。值与化合物的前沿轨道能级以及取代基效应之间的相关性,结果较为满意,从而证明从该体系测得的ｐＫａ值用于构效关系分析是完全可行的。     

N-和对位取代苯胺及其正离子基在二甲亚砜溶液中的酸性解离常数

本文报道了在DMSO中测定的N-取代苯胺和对位取代乙酰苯胺的酸性解离常数[pK_a(HA)].利用热力学循环原理,通过对pKa和中性分子及其共轭碱的氧化电位的测定,求得了用直接方法难以得到的正离子基的酸性解离常数[pK_a(HA^+·)],并对所得的pK_a(HA)和pK_a(HA^+·)的取代基效应进行了讨论。     

含有单取代嘧啶的新型磺酰脲类化合物的设计、合成及除草活性

为了寻找高效的磺酰脲类除草剂, 以商品化磺酰脲类除草剂为基础, 将单取代嘧啶结构引入到分子中, 合成了一系列新型磺酰脲类化合物, 并通过¹H NMR和高分辨质谱确定了其结构. 采用盆栽法和平皿法测试了所有化合物的除草活性以及部分化合物对油菜的IC₅₀值. 结果表明, 一些化合物具有一定的除草活性, 其中化合物7b和7d对油菜和反枝苋具有较好的抑制活性.     

金属萃取反应中烷基磷(膦)酸及其酯的化学结构与性能的定量关系研究

根据三十八个一元烷基磷(膦)酸的pK_a值可以求得各个取代基团的经验结构参数σ^ρ。     

L-对甲苯磺酰乳酸乙酯合成物产率的化学分析法

建立了采用 K2 Cr O4 - K2 Cr2 O7混合指示剂测定 L-对甲苯磺酰乳酸乙酯合成物产率的化学分析方法 ,K2 Cr O4 - K2 Cr2 O7的最佳配比为 K2 Cr O4 ∶ K2 Cr2 O7=6∶ 1 (m/m) ,体系的最佳酸度为 p H5.8,测得 L-乳酸乙酯与甲苯磺酰氯反应制备的 L-对甲苯磺酰乳酸乙酯的产率为 94.0 %。     

新型导电盐(三氟甲基磺酰)(三氟乙氧基磺酰)亚胺锂及其非水电解液的制备与性能

制备了一种新型含氟磺酰亚胺锂盐(三氟甲基磺酰)(三氟乙氧基磺酰)亚胺锂{Li[(CF₃SO₂)·(CF₃CH₂OSO₂)N], Li[TFO-TFSI]}及其与碳酸乙烯酯(EC)/碳酸甲乙酯(EMC)混合溶剂(3∶7, 体积比)组成的非水电解液. 采用核磁共振波谱(NMR)、 红外光谱(IR)、 质谱(MS)、 元素分析(EA)和离子色谱(IC)等手段对合成锂盐Li[TFO-TFSI]进行了结构表征及纯度分析. 通过差示量热扫描(DSC)和热重分析(TG)对Li[TFO-TFSI]及其电解液1.0 mol/L Li[TFO-TFSI]-EC/EMC(3∶ 7)的热学性质进行了表征. 采用交流阻抗(EIS)、 循环伏安(CV)、 计时安培法及扫描电子显微镜(SEM)等对Li[TFO-TFSI]/碳酸酯电解液的基础物化和电化学性质进行了表征. 结果表明, Li[TFO-TFSI]/碳酸酯电解液具有较好的电化学稳定性; 在4.2 V(vs. Li/Li⁺)以下Al箔不发生腐蚀; 室温下基于Li[TFO-TFSI]/碳酸酯电解液的Li/人造石墨和人造石墨/LiCoO₂电池均保持较好的循环性能, 特别是人造石墨/LiCoO₂锂离子电池循环100周后, 其比容量保持率明显高于相应的基于LiPF₆/碳酸酯电解液体系的电池.     

带有苯酚侧臂的四氮大环Zn(Ⅱ)配合物催化羧酸酯水解研究

合成并表征了在大环侧臂引入取代苯酚作为功能基团的新型四氮大环配体(L₁,L₂和L₃).对配体L₃的质子化过程及其与Zn(Ⅱ)的配位过程的研究表明,配体中的酚羟基与四氮大环环中的质子之间存在较强的氢键.测得配体及配合物中酚羟基的pK_a分别为8.3和8.5.考察了上述3个配体的Zn(Ⅱ)配合物作为水解锌酶的模拟物催化对硝基苯酚乙酸酯(NA)水解的动力学行为,测得它们催化NA水解的二级反应速率常数k_c/［(mol/L^-1·s^-1］分别为3.48×10^-2、1.52×10^-2和2.85×10^-2.     

L—对苯磺酰乳酸乙酯合成物产率的化学分析法

建立了采用K2CrO4-K2Cr2O7混合指示剂测定L－对甲苯磺酰乳酸、乙酯合成物产率的化学分析方法,K2CrO4-K2Cr2O7的最佳配比为K2CrO4：K2Cr2O7＝6：1（m/m）,体系的最佳酸度为pH 5.8,测得L－乳酸乙酸与甲苯磺酰氯反应制备的L－对甲苯磺酰乳酸乙酯的产率为94.0％。     

羧酸类化合物的结构和萃取性能的相关性

应用量子化学参数研究羧酸类化合物的结构与其萃取性能的相关性,并将二维结构参数应用到三维构效关系研究中,从而有效地改善了CoMFA法的结果,用pK_a值来表征羧酸类化合物的萃取性能.     

四丁基碘化铵/过硫酸钾体系促进硝基烯烃与磺酰肼脱硝磺酰化反应合成(E)-β-烯基砜

发展了一种硝基烯烃与磺酰肼脱硝磺酰化反应合成(E)-β-烯基砜。 以四丁基碘化铵(TBAI)/过硫酸钾(K₂S₂O₈)为催化氧化体系,多种硝基苯乙烯衍生物与取代磺酰肼发生自由基加成/脱硝基反应,以中等到良好的收率获得各种(E)-β-烯基砜。 反应具有底物适用范围广、反应操作简单、无金属催化及中性反应条件等优点,为含β-烯基砜类化合物的合成提供了一条高效、简单、环境友好的新途径。     

保留型与反转型β-木糖苷酶活性位点的分子动力学模拟

木聚糖是潜在的重要可再生能源, 如何提高其降解效率已成为近年来的研究热点. β-木糖苷酶是木聚糖降解过程中的关键酶之一, 按其水解机制可分为保留型与反转型酶. 目前虽然对于这两种催化机制的研究不断深入, 但很少有工作从溶液环境的角度出发探究它们的差异. 本文采用分子动力学模拟方法, 对4 个典型的β-木糖苷酶进行了显式溶剂模拟研究, 详细分析了酶的催化氨基酸间的距离和质子供体氨基酸pK_a值的动态变化. 结果显示, 反转型酶催化氨基酸间的距离约为0.8-1.0 nm, 大于保留型的0.5-0.6 nm, 与先前对糖苷酶晶体结构的统计分析结果一致. 令人意外的是, 保留型酶的质子供体通过与其附近组氨酸的相互作用, 其pK_a在两个不同的高、低值之间交替变换, 使保留型酶的双取代反应得以发生; 而反转型酶的质子供体则由附近的天冬氨酸调节, 其pK_a稳定在某个较高值, 这可能有利于其在反应pH值下获得水溶液中的氢离子, 进行反转型酶特有的单取代反应. 因此, 本工作加深了人们对β-木糖苷酶保留型与反转型水解机制的认识, 并为后续酶的理性改造与高效利用提供具有指导价值的结构与机理信息.     

Solubility prediction of anthracene in mixed solvents using a minimum number of experimental data

Numerical methods to predict the solubility of anthracene in mixed solvents have been proposed. A minimum number of 3 solubility data points in sub-binary solvents has been employed to calculate the solvent-solute interaction terms of a well established colsolvency model, i.e. the combined nearly ideal binary solvent/Redlich-Kister model. The calculated interaction terms were used to predict the solubility in binary and ternary solvent systems. The predicted solubilities have been compared with experimental solubility data and the absolute percentage mean deviation (APMD) has been computed as a criterion of prediction capability. The overall APMD for 25 anthracene data sets in binary solvents is 0.40%. In order to provide a predictive method, which is based fully on theoretical calculations, the quantitative relationships between sub-binary interaction terms and physicochemical properties of the solvents have been presented. The overall APMD value for 41 binary data sets is 9.19%. The estimated binary interaction terms using a minimum number of data points and the quantitative relationships have then been used to predict anthracene solubility data in 30 ternary solvent systems. The produced APMD values are 3.72 and 15.79%, respectively. To provide an accurate correlation for solubility in ternary solvent systems, an extension to the combined nearly ideal multicomponenet solvent/Redlich-Kister (CNIMS/R-K) model was proposed and the corresponding overall AMPD is 0.38%.     

Reactivity of azoles towards benzaldehyde and its dimethylacetal. Synthesis of N,N''-diazolylphenylmethanes

Some 1,1'-diindazolylphenylmethanes have been prepared from indazoles and benzaldehyde in presence of zinc chloride as catalyst. The reaction was strongly dependent on the basic pK_a 's of azoles and only few pyrazolyl derivatives could be prepared by this procedure. Extension of this method to other azoles was accomplished by using benzaldehyde dimethylacetal.     

络合物稳定常数的计算

本文介绍了计算络合物稳定常数的八种方法,它们是:1.lgK₁=Az²/r+Bx_±+C.2.两相似金属离子与一系列配位体络合时,lgK₁间一的线性关系。3.两相似配位体与一系列金属离子络合时,lgK₁间的线性关系。4.一系列相似配位体与同一金属离子络合时,lgK₁与∑pK_a间的线性关系。5.一系列相近z²/r的金属离子与同一配位体络合时lgK₁与x_±间的线性关系。6.一系列相近x的金属离子与同一配位体络合时lgK₁与z²/r间的线性关系。7.金属离子随z²/r和x而变化的络合次序。8.∑pK_a较大的配位体与z²/r较大的金属离子匹配,电负性较小的配位体与电负性大的金属离子匹配。     

分析量子化学研究(Ⅱ)——光度分析新显色剂对甲基偶氮氯膦离解与质子化作用及其机理

对甲基偶氮氯膦(CPApM)作为不对称偶氮氯膦类光度分析显色剂,已应用于稀土氧化物与有关矿石、镍基合金中测定钇的含量,本文以分光光度法测得了CPApM的离解常数及质子化常数,运用HMO法进行半经验量子化学计算,并对其电子结构、离解作用与质子化作用及微观机理作了探讨。     

Investigation of the structure of and the properties of the potentially tautomeric 1,2,3,4-tetrahydro-5,7-dimethyl-6H-pyrrolo[3,4-d]pyridazine-1,4-diones in the gaseous and aqueous phases using the AM1 semi-empirical method

Potentially tautomeric 1,2,3,4-tetrahydro-5,7-dimethyl-6H-pyrrolo[3,4-d]pyridazine-1,4-diones and their fixed tautomeric forms have been studied in order to predict their tautomeric equilibrium constants and pK_a values using semi-empirical AM1 quantum-chemical calculations at the SCF level in the gas phase and in aqueous solution. Hydroxy-oxo forms were found to be more stable than dioxo and dihydroxy forms. The results obtained from the tautomeric equilibria and basicity calculations are in good agreement with experimental data.     

四苯基卟啉及其衍生物的结构与性质研究(Ⅳ)——二质子四苯基卟啉及其衍生物的光谱、pKa与取代基常数间的线性关系

以HMO法剖析了二质子四苯基卟啉(H₂TPP²⁺)及其衍生物的紫外-可见光谱,确定了四苯基卟啉(TPP)和H₂TPP²⁺及其衍生物的λ_max、pK_a与取代基常数σ间的线性关系。     

硅胶自溶液中吸附胆固醇和卵磷脂

卵磷脂和胆固醇是细胞膜的主要组成,它们在不同界面上的定向排列方式对细胞膜的结构与功能起着重要的作用。用固体物质自非水溶剂中吸附类脂化合物形成类脂单层,再自水溶液中吸附蛋白质,可制成固体载体上的模拟生物膜。在固体表面上的类脂单层膜中类脂分子的定向方式与溶剂和固体表面性质有关。这些研究大多数是以非孔性物质为吸附剂(如aerosil,石墨化炭黑,carbochrom.等)自有机溶剂中吸附类脂化合物(主要是胆固醇和卵磷脂),根据单层饱和吸附时分子占据的面积推算单层中类脂化合物分子的取向。实际应用的吸附剂大多是孔性的,因此研究类脂化合物在孔性吸附剂(如,硅胶、活性炭等)上的吸附机理更有实际意义。     

A computational analysis of the structural features and reactive behavior of some heterocyclic aromatic N-oxides

An ab initio self-consistent-field molecular orbital analysis of the structural features and reactive behavior of pyridine, pyrazine and some of their N-oxide and nitro derivatives has been carried out. Optimized structures have been computed at the 6-31G^* level, yielding geometries in good agreement with experiment. These structures have been used to compute STO-5G electrostatic potentials and average local ionization energies on the respective molecular surfaces. There is considerable conjugation between the N-oxide groups and the aromatic rings, leading to significant para-quinonoid influence, manifested both in terms of structures and reactive properties. The charge-donor role of the N-oxide group allows the aromatic ring in pyridine N-oxide to be susceptible to electrophiles (at the para position) as well as nucleophiles; however, the rings in the pyrazine oxides are only receptive to the latter. The local ionization energies have permitted predictions of pK_a values for pyrazine N-oxide and p-nitropyridine.     

Triplet excited states and radical intermediates formed in electron pulse radiolysis of amino-substituted fluorenones

Electron pulse radiolysis of four differently substituted amino derivatives of fluorenone, namely, 1-amino-, 2-amino- 3-amino-, and 4-aminofluorenone, has been carried out to study the effect of structure on the spectroscopic and kinetic characteristics of the triplet excited states as well as the transient free radical intermediates formed under reducing and oxidizing conditions. The triplet states of these compounds have been generated in benzene by pulse radiolysis and in other solvents by flash photolysis technique and their spectral and kinetic properties have been investigated. Hydrated electron (e_aq⁻) has been found to react with these fluorenone derivatives to form the anion radical species with a diffusion-controlled rate constant. The spectral and kinetic properties of the transient ketyl and anion radicals have been studied by generating them in aqueous solutions of suitable pH. The pK_a values of ketylanion radical equilibria are in the range of 6.8–7.7 for these derivatives. The oxidized species have been generated by reaction with the azide radical. Hydrogen atom adducts as well as the cation radicals of these derivatives have also been generated by pulse radiolysis and characterized.