Fischer Synthesis of 1-; 5-; and 7-Substituted 3-(N-Acylamino)-2-phenylindoles

Arylhydrazones were obtained by the reaction of arylhydrazines with -(N-acylamino)acetophenones and were converted into 3-(N-acylamino)-2-phenylindoles with substituents at positions 1, 5, 6, and 7 by Fischer cyclization.     

Fluorimetric determination of ascorbic acid with o-phenylenediamine

A simple and sensitive fluorimetric method for the determination of ascorbic acid (AA) is described. The method is based on the condensation reaction between AA and o-phenylenediamine (OPDA) in the absence of the oxidant. The fluorescence intensity is measured at excitation and emission wavelengths of 360 and 430 nm, respectively. Under optimum condition, a linear relationship is obtained between the fluorescence intensity and the concentration of AA in the range of 0.05-40 μg ml⁻¹. The detection limit is 0.006 μg ml⁻¹, which is obviously lower than that of other fluorimetric methods reported.     

Oxovanadium(V)-catalyzed enantioselective Meerwein-Ponndorf-Verley cyanation of aldehydes using acetone cyanohydrin

Oxovanadium(V)(salen) complex 4 was found to catalyze Meerwein-Ponndorf-Verley cyanation of aliphatic aldehydes with good to high enantioselectivity. This cyanation showed a positive nonlinear effect.     

基于交叉共轭结构的功能材料

近年来,人们对交叉共轭体系的制备、性能以及理论研究方面产生了极大的兴趣。本文综述了近期国内外在交叉共轭体系研究方面取得的一些最新进展,重点介绍了其在自组装、有机电致发光和离子检测等方面的最新发展动态。最后还对本课题组在交叉型p-n双嵌段寡聚物方面的研究作了详细的介绍,并对一些热点问题作了展望。     

PPC/SBR并用弹性体的配方选择

利用正交法对丁苯橡胶（SBR）／聚丙撑碳酸酯（PPC）共混弹性体进行配方设计，得到了一个具有良好综合性能的配方。并通过方差分析得出PPC含量和马来酸酐（MA）用量是影响弹性体拉伸性能的最显著因素。     

1,2,2-Trimethyldisilane-1,1,2-triol: intermediate formation and conversion to condensation products

1,2,2-Trimethyldisilane-1,1,2-triol (1) is formed as an unstable intermediate upon hydrolysis of oligo(trimethyldisilanylsesquiazane). In the absence of trapping agents it undergoes rapid condensation to give ether-soluble poly(trimethyldisilanyloxane) which contains silanol groups. Treatment of the hydrolysis products with chlorotrimethylsilane in the presence of triethylamine affords trimethylsiloxy derivatives, (Me₃SiO)₂MeSiSiMe₂(OSiMe₃),5,6, and [Si₂Me₃O _x (OSiMe₃) _y ] _n . The isolation of these products indicates that disilanetriol1 readily undergoes condensation to form hydroxylcontaining six-membered rings and polysiloxanes. The condensation of compound1 in the presence of Me₃SiOH has been studied. The ratio between the isomeric cyclosiloxanes5 and6 has been determined both by¹H NMR spectroscopy and by a chemical method (chlorinolysis). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1788–1792, October, 1993.     

卟啉镍分子的激发态和反饱和吸收

用INDO/CI方法研究了卟啉镍分子的电子结构、紫外光谱、激发态,并从理论上指出卟啉镍分子存在反饱和吸收的微观机制.     

THE SEPARATION,PURIFICATION AND DECOLORIZATION OF NEW ANTIBIOTICS-MILUPEINAN USING ADSORPTION RESIN

1. INTRODUCTION Fig.1 The Chemical Structure of Milupeinan As a new type of antibiotics Milupeinan, not only possesses antibacterial activities against a wide range of Gram-positive and Gram-negative bacteria, but also higgh stability under th…     

Das asymptotische Verhalten der Peanokerne einiger interpolatorischer Quadraturverfahren

Summary Interpolatory quadrature formulae consist in replacing by wherep _f denotes the interpolating polynomial off with respect to a certain knot setX. The remainder may in many cases be written as wherem=n resp. (n+1) forn even and odd, respectively. We determine the asymptotic behaviour of the Peano kernelP _X (t) forn for the quadrature formulae of Filippi, Polya and Clenshaw-Curtis.

     

Characterization of SiO2-P2O5-ZrO2 Sol-Gel/NAFION™ Composite Membranes

Composite membranes were prepared by (a) infiltrating NAFION with SiO₂-P₂O₅-ZrO₂ sol, and (b) recasting a film using NAFION solution containing SiO₂-P₂O₅-ZrO₂ sol. The membranes were characterized by Differential Thermal Analysis and ac-impedance spectroscopy as a function of relative humidity. The influences of the heat treatment (80°C–150°C) and cleaning on the electrical properties were investigated. The incorporation of SiO₂-P₂O₅-ZrO₂ gels into NAFION lead to improvements in its thermal stability and proton conductivity.