Determination of Diffusion Coefficients for Binary Nonelectrolyte Mixtures. A Free-Volume Predictive Approach

A diaphragm cell has been used to measure mutual diffusion coefficients at 25°C for four binary nonelectrolyte mixtures: ethylbenzene + n-hexane, carbon tetrachloride + ethylbenzene, cyclohexane + p-xylene, and 1,2-dichloroethane + cyclohexane. A free-volume predictive approach for binary mutual diffusion coefficients was developed and tested. Only infinite dilution diffusion coefficients, some readily available pure substance data, and UNIFAC group contribution parameters are used in the model. No binary equilibrium thermodynamic information is required. For 73 binary systems with an overall average absolute deviation of 5.2%, it has been shown that the developed method is better than two commonly available reference methods for the prediction of liquid diffusion coefficients.     

超声波作用下羰基化合物的还原偶联反应

超声波在一些有机反应中有明显的促进作用「“，Luche等认为超声波的作用有两种主要类型［’j．一类是涉及电子转移的自由基或离子一自由基型反应，由于超声波的空化作用所产生的局部高温高压可以促进电子转移，从而明显地加快反应速度；对大多数离子型反应，超声波只能起到机械的物理作用．我们曾报道偕二卤化合物在Li、Na、Mg等金属作用下产生卡宾的反应是单电子转移过程，该反应可由于超声辐射而大大加速［‘］；而在芳基叔脚的断裂反应中，超声波可以促进三苯基俄与金属馊反应生成二苯基脚负离子，但对它进一步的亲核取代反应却没有明…     

A Minor New Flavone from Scutellaria baicalensis Georgi

A new flavone,6,2′-dihydroxy-5,7,8,6′-tetramethoxyflavone,was isolated from the roots of Scutellaria baicalensis. Its structure was established on the basis of spectral evidences.     

51VNMR研究磷钼钒系杂多酸的热稳定性

用NMR及IR、TG-DTA等手段研究具有Keggin结构的磷钼钒系杂多酸在空气中的热稳定性。实验结果表明:合成的杂多酸在各个Keggin单元中具有不同的钒含量。样品的热稳定性与其钒含量有关.随着钒含量的增加,keggin结构的热稳定性逐渐降低,但H_4PMo_(11)V_1O_(40)具有比H_3PMo_(12)O_(40)还要高的热稳定性。由于钒的取代,钼钒磷酸的热分解过程不同于钼磷酸。失去结构水使Keggin结构遭到破坏,但在室温下与水重新作用可使钼钒磷酸的Keggin结构恢复。     

单核零价过渡金属配合物的研究——Ⅱ.含有π-键合醌及双齿氮配体的混配零价钯配合物的合成与表征

本工作合成了一系列十个新的零价钯混配配合物,并对这些配合物进行了表征.研究了配体的立体效应和电子效应的差别,讨论了配体间的相互作用.一.配合物的合成与组成据文献合成dba(PhCH=CHCOCH=CHPh)和Pd_2(dba)_3(CHCl_3).其余试剂及溶剂均为市售商品,用前经无水无氧处理.     

A Study of the Silylation of 1,8-Dihydroxynaphthalene

Twelve compounds each having a six membered Si-contained heterocycle, have been successfully synthesized. Of these eleven compounds have never been reported in the literature. The structures were confirmed by Spectral analysis and elementary analysis. The stability and properties of these compounds is also discussed.     

Electrochemical characteristics of a platinum electrode modified with a matrix of polyvinyl butyral and colloidal Ag containing immobilized horseradish peroxidase

A new hydrogen peroxide biosensor was constructed, which consisted of a platinum electrode modified by a matrix of polyvinyl butyral (PVB) and nanometer-sized Ag colloid containing immobilized horseradish peroxidase (HRP), and using Co(bpy)₃³⁺ as mediator in the hydrogen peroxide solution. The electrochemical characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. The modified process was characterized by electrochemical impedance spectroscopy and cyclic voltammetry. The HRP immobilized on colloidal Ag was stable and retained its biological activity. The sensor displays excellent electrocatalytic response to the reduction of H₂O₂. Analytical parameters such as pH and temperature were also studied. Linear calibration for H₂O₂ was obtained in the range of 1×10^–5 to 1×10^–2 M under optimized conditions. The sensor was highly sensitive to H₂O₂, with a detection limit of 2×10^–6 M, and the sensor achieved 95% of steady-state current within 10 s. The sensor exhibited high sensitivity, selectivity and stability.     

以有机镍配合物为前体制备担载镍催化剂的研究

描述了以镍单核配合物ＮｉＣｐ２和簇合物Ｎｉ３Ｃｐ３Ｎ－ｔ－Ｃ４Ｈ９为前体的ＳｉＯ２载镍催化剂的制备，通过元素分析、ＴＲＲ、ＴＰＤＥ、ＸＰＳ，ＣＯ吸附和苯加氢反应对以镍配合物和簇合物为前体制备的催化剂的性能及其制备过程了研究和表征。结果表明，镍与合物和簇合物在担载过程中同载体ＳｉＯ２表面发生了相互作用，其化学组成发生了变化，在苯加氢反应中，此催化剂的活性比以Ｎｉ（ＮＯ３）２为前体制备的催化剂高得多，     

药物分子在玻碳电极上的电分析化学研究──Ⅴ．安乃近的伏安行为及测定

提出了一种测定安乃近新法。由于安乃近没有电活性，故将安乃近和盐酸在１００℃共热后生成电活性产物，用玻碳电极在０．１ｍｏｌ／ＬＮａＯＨ中得一良好的阳极氧化伏安峰，Ｅｐ＋０．３５Ｖ（ｖｓ·Ａｇ／ＡｇＣｌ）左右，峰电流与安乃近浓度在０．１～１００ｍｇ／Ｌ之间呈线性关系，分析了制剂安乃近的含量，实验证实电极反应属于扩散控制的不可逆过程。     

锰（Ⅱ）—邻菲口罗啉配合物极谱吸附波及其应用

在ｐＨ９．５ＮＨ３ＮＨ４Ｃｌ缓冲溶液中，Ｍｎ（Ⅱ）与邻菲口罗啉形成的配合物在－１．３６Ｖ（ｖｓ．ＳＣＥ）处产生一灵敏的吸附波，一阶导数峰电流与Ｍｎ（Ⅱ）浓度在５×１０－８５×１０－６ｍｏｌ／Ｌ范围内呈线性关系，检出限为２×１０－８ｍｏｌ／Ｌ对极谱性质及反应机理进行了研究，用该法测定了大豆和茶叶中的微量锰，结果满意