Simultaneous spectrophotometric determination of molybdenum and selenium,and of molybdenum and tellurium

A method is reported for the extraction of molybdenum-phenylfluorone by chloroform. The extraction is complete whether perchlorate ions are present or not but the extractions in the presence of perchlorate ions gave a somewhat more sensitive procedure for the spectrophotometric determination of molybdenum in the solvent phase as the molybdenum-phenylfluorone complex.A procedure is reported for the simultaneous determination of molybdenum and selenium, and molybdenum and tellurium. The method involves first the formation and solvent extraction of the molybdenum-phenylfluorone complex by chloroform in the presence of perchlorate ions, followed by determination of selenium in the remaining aqueous phase as selenium-diethyldithiocarbamate complex after solvent extraction with 2-ethyl-1-hexanol in the presence of perchlorate ions. A similar procedure is reported for the simultaneous determination of molybdenum and tellurium except that in the determination of molybdenum, the phenylfluorone complex is extracted by chloroform in the absence of perchlorate ions. Tellurium is determined in the remaining aqueous phase as tellurium-diethyldithiocarbamate complex after solvent extraction by 2-ethyl-1-hexanol solvent extraction in the presence of perchlorate ions.     

三氯环硼氮烷和聚硼氮烷的合成与表征

以三氯化硼和氯化铵为原料,甲苯为溶剂,高产率(98%)地合成了具有硼和氮的六元环结构的三氯环硼氮烷(1);1分别与正丙胺(Ⅰ)和异丙胺(Ⅱ)反应制得正丙胺基环硼氮烷(1~Ⅰ)和异丙胺基环硼氮烷(1~Ⅱ);1~Ⅰ和1~Ⅱ经过脱胺和热聚合反应制得聚硼氮烷先驱体(2和3).用IR,NMR和XRD等对2和3的组成与结构进行了分析,探讨了聚硼氮烷的胺基取代基对聚硼氮烷聚合反应性及产物结构的影响.研究结果表明,3具有更强的热聚合特性.     

Ozonolysis and combination of ozonolysis and radiolysis of aqueous fluorene

The degradation of fluorene, a toxic and carcinogenic substance formed by combustion of fossil fuels, was studied in alkaline, aqueous solution. It is very efficiently decomposed by ozonation, where 9-fluorenone and 9-fluorene carboxylic acid appear as major products in addition to a mixture of aldehydes and carboxylic acids. A more efficient substrate decomposition was observed by a treatment with γ-rays in the presence of ozone. The yield of the main products was in the case 4-times lower compared to those obtained by ozonation only. Some probable reaction steps are presented for explanation of the products.     

Preparation and characterization of uniform particles of flufenamic acid and its calcium and barium salts

Uniform fully dispersed particles of flufenamic acid, a widely used anti-inflammatory drug, were prepared by two different methods. In the first one, the drug solution in organic solvents was added to a non-solvent (water or aqueous solutions of stabilizers); while in the second procedure the drug was precipitated by acidifying its basic aqueous solutions. In addition calcium and barium salts of uniform spherical particles were obtained by precipitation in aqueous basic solutions of the drug. These salts are supposed to improve the drug reactivity. The prepared dispersions of the drug and its salts were examined by scanning electron microscopy, X-ray diffractometry and electrophoresis.     

Direct and sensitized photoprocesses of bis-benzimidazole dyes and the effects of surfactants and DNA

The photoprocesses of two bis-benzimidazole dyes, Hoechst 33258 (1) and an analog, where the phenolic group in p-position is replaced by an ethoxy group, Hoechst 33342 (2), were studied. For 1 and 2 in aqueous solution the quantum yield of fluorescence is strongly pH dependent; it decreases from a maximum value of phi f = 0.4 at pH 5 to phi f = 0.02 at pH 8. The effects of absorption and fluorescence, induced by sodium dodecyl sulfate surfactants below and above the critical micelle concentration and by double-stranded DNA, are interpreted by assuming that in bulk aqueous solution the dyes are essentially present as monomers. The strong enhancement of phi f, when the dye is bound to double-stranded DNA or solubilized in micelles, is suggested to be due to different environments at the benzimidazole rings. A quinoid intermediate with absorption maximum at 380 nm is formed for 1 at neutral pH using lambda exc = 248 or 308 nm. N-centered radicals of 1 or 2 in aqueous solution were observed by laser flash photolysis after electron ejection using wavelengths of 193 or 248 nm (mono and biphotonic, respectively). The precursor radical cation escaped observation but is transformed into the above radicals by deprotonation. Electron transfer from 1 in aqueous solution to triplet acetone takes place, and subsequent deprotonation is proposed to yield N-centered radicals. In addition, energy transfer from acetone to 1 is suggested, leading to T-T absorption with the maximum at 700 nm. The photoprocesses are discussed and the results compared with those known from pulse radiolysis.     

Synthesis of pyrazolo-enaminones,bipyrazoles and pyrazolopyrimidines and evaluation of antioxidant and antimicrobial properties

A novel pyrazolo-enaminones, bipyrazoles and bipyrazolopyridines from 1-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)butane-1,3-dione and 4-methyl-2-phenyl-2H-pyrazolo[3,4-b]pyridine-3,6(3aH,7H)-dione have been synthesized by assisted heating with microwave radiation without any catalyst. The pyridine and pyrazole ring formation has been developed from easily accessible enamino keto esters by formylation followed by intramolecular cyclization. The general applicability for the synthesis of the important pyrazolo-enaminones, bipyrazoles and pyrazolo-pyridines heterocycles was attributed to simplicity of operation, synthesis without catalyst, energy efficiency (shorter reaction time under microwave irradiation), good yields, more environmentally friendly and more cost-effective procedure. The antioxidant activity of new heterocyclic compounds was evaluated by free radical scavenging by DPPH assay. Several of these compounds showed good activity against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria.     

硫/碳纤维复合膜的制备及电化学性能

采用热丝化学气相沉积法先在铁箔上沉积了致密的碳纤维膜,后通过加热渗硫法制得硫/碳纤维复合膜,并将其用作锂硫电池正极材料。通过扫描电子显微镜和X射线衍射表征膜的形貌和结构,采用恒流充放电法和阻抗测量法测试复合膜的电化学性能。结果表明,随热丝与铁箔基底间距减小,碳纤维膜致密度先升高后降低;随H2与(Ar+C3H6O)的体积流量比减小,碳纤维膜致密度升高。当丝基距为6 mm,流量比为30/40时,铁箔上沉积了厚度为50μm的致密碳纤维膜,其中碳纤维有良好的垂直取向性和较高结晶度。在硫/碳纤维复合膜正极中,密集的碳纤维形成均匀分布且垂直取向性良好的导电骨架,当电流密度为0.4 mA.cm-2时,硫/碳纤维复合膜正极的初次放电比容量为1 128 mAh.g-1,50次循环后的放电比容量为811 mAh.g-1。     

水溶性半胱氨酸和高半胱氨酸探针的合成及应用

以对硝基甲苯和变色酸为原料,经硝化、重氮化反应合成了水溶性偶氮化合物(1),其结构经1H NMR和元素分析表征.利用UV-vis滴定法研究了在缓冲溶液(pH 7.4)中1对半胱氨酸(Cys)和高半胱氨酸(Hcy)的识别能力.结果表明:1与Cys或Hcy作用后引起吸收光谱蓝移～69 nm,能够用于Cys和Hcy的裸眼识别.     

Determination and differentiation of nitrilotriacetic acid and ethylenediaminetetra-acetic acid

Ethylenediaminetetra-acetic acid (EDTA) and nitrilotri-acetic acid (NTA) can be differentiated and determined by titration with metal ions to visual metallochromic dye end-points. EDTA can be determined without interference from NTA, either by titrating with copper(II) at pH 5 using PAN indicator, or by titrating with iron(III) at pH 6 and 70 degrees using Tiron indicator. The total chelating power (EDTA + NTA) can be determined either by titrating with lead(II) at pH 4.4 using dithizone indicator, or by titrating with iron(III) at pH 3.5 using Tiron indicator ; NTA is determined by difference. The lowest concentration at which NTA can be determined in EDTA by titration to the iron(III)-Tiron end-point is about 1 wt.%. The apparent stability constants of the iron(III)-Tiron complexes under the conditions of the titration at pH 3.5 and pH 6 have been determined using the method of continuous variations.     

Preparation of cyclopentadienes and diazocyclopentadienesvia cyclopentenolones and cyclopentenones

The structure and stereochemistry of the cyclopentenolones obtained by condensation of dialkyl ketones with benzil have been studied by NMR spectroscopy. These enolones were converted into cyclopentenones and cyclopentadienes. Alkyl-substituted cyclopentadienes required phenyllithium to effect their conversion by toluenesulphonyl azide into diazo-cyclopentadienes; otherwise piperidine sufficed as base catalyst.2,3,4-Triphenyldiazocyclopentadiene was simply procured by reaction of the condensation product of benzil and phenylacetone with toluenesulphonylhydrazone followed by alkali. Cyclohexyl- and methoxy-triphenylcyclopentadienes were prepared by photolytic decomposition of diazotriphenylcyclopentadiene in cyclohexane or methanol respectively.     

Oxidations and reductions of iron-cyanogen compounds of cobalt,nickel, cadmium and zinc

I. Cobalt ferrocyanide is oxidized by bromine water, by nitrous acid or by hydrogen peroxide in presence of acids to cobalt ferroferricyanide (cobalt Prussian blue), while cobalt ferricyanide is reduced by sulfurous acid to cobalt Prussian blue.II. Nickel ferrocyanide is oxidized by nitrous acid or by hydrogen peroxide in presence of acids to nickel ferricyanide.III. Nickel ferrocyanide and cadmium ferrocyanide are oxidized by bromine water to the ferricyanides.IV. The ferricyanides of nickel, cadmium and zinc are reduced by sulfurous acid to the ferrocyanides.     

Synthesis and characterization of copolyesters of PET and substituted p-hydroxybenzoic acids

Random copolyesters of different compositions were synthesized by melt polycondensation of poly(ethylene terephthalate) and 3-bromo - and 3,5-dibromo-p-hydroxybenzoic acids. The copolymer compositions were determined by proton nuclear magnetic resonance spectroscopy. The thermal behavior of these copolyesters was investigated by differential scanning calorimetry. The glass transition temperature, crystallization temperature, and decomposition temperature were found to increase with increase in the paraoxybenzoate content of the copolyesters. The limiting viscosity number and the weight-average molecular weight were determined.     

Stereoselective synthesis of cis and trans n-tosyl sulphilimines and sulphoxides from 2-alkylthianes and 2-alkylthiolanes assignments of configurations

Thiane and thiolane derivatives with 2-methyl, 2-ethyl, 2-isopropyl and 2-tert-butyl groups were prepared and converted to cis and trans sulphilimines and sulphoxides by various stereoselective methods. Cis-sulphilimines were formed by using t-BuOCl and TsNH^- in a two-stage process, while cyclic sulphides were converted by chloramine-T predominantly to trans-sulphilimines. Sulphoxides enriched in cis and trans isomers were obtained by different methods of oxidation. Diastereoisomeric product distributions were measured by hplc and the configurations of diastereoisomers were assigned by ¹³C NMR spectroscopy. Preferred conformations of sulphilimines were determined by analysis of ¹³C NMR and X-ray data. As shown by ¹³C NMR spectra, the conformations of sulphilimines and sulphoxides are analogous.     

Synthesis and characterization of amphiphilic star copolymer of beta-cyclodextrin and polypropylene oxide and their application as nanocarriers

The present study was aimed at synthesizing and characterizing star copolymers of ??-cyclodextrin and exploring their application as nanocarriers. The copolymers of ??-cyclodextrin and polypropylene oxide were synthesized by using ring opening polymerization, catalyzed by base, under high temperature and pressure. The polymers of different molecular weight were synthesized by increasing chain length of polypropylene oxide at optimized temperature, pressure and concentration of catalyst. The structure of synthesized polymer was confirmed by IR and NMR. Molecular weight and molecular weight distribution was evaluated by hydroxyl number and gel permeation chromatography respectively. Amphiphilic nature of the polymers was evaluated by determining the solubility in water and different organic solvents. For the evaluation of polymer as a nanocarrier, Ibuprofen was selected as model drug. Loading efficiency and release of Ibuprofen from the complex were also investigated. It was observed that, with increase in the molecular weight of the polymers, loading capacity was increased.     

Kinetics and thermodynamics of the adsorption of some dyestuffs and p-nitrophenol by chitosan and MCM-chitosan from aqueous solution

The effect of initial concentration, temperature, and shaking rate on the adsorption of three dyestuffs [orange II (O-II), crystal violet (CV), and reactive blue 5 (RB5)] and an ideal adsorbate, p-nitrophenol (PNP), by chitosan (Sigma C-3646) and the effect of temperature on the adsorption of O-II and CV by monocarboxymethylated chitosan (MCM-chitosan) were investigated. Kinetic data obtained for the adsorption of each dyestuff and PNP by chitosan and of O-II and CV by MCM-chitosan at different temperatures were applied to the Lagergren equation, and adsorption rate constants (k(ads)) at these temperatures were determined. These rate constants related to the adsorption of O-II and RB5 by chitosan and of O-II by MCM-chitosan were applied to the Arrhenius equation, and activation energies (E(a)) were determined. In addition, the isotherms for adsorption, at different temperatures, of each dyestuff and PNP by chitosan and of O-II and CV by MCM-chitosan were also determined. These isothermal data were applied to linear forms of isotherm equations that they fit, and isotherm constants were calculated. Because the isotherm curves obtained for the adsorption of O-II and CV by chitosan and of CV by MCM-chitosan fit the Langmuir adsorption isotherm, b constants were applied to thermodynamic equations, and thermodynamic parameters (delta G, delta H, and delta S) were calculated. Lastly, chitosan and MCM-chitosan were compared with respect to the ability to take up the dyestuffs and PNP.     

去甲氯胺酮半抗原及其全抗原的合成与鉴定

在低温条件下,去甲氯胺酮与琥珀醛酸反应,合成了半抗原羧基-去甲氯胺酮,电喷雾质谱鉴定结果表明,目标半抗原合成成功;通过碳二亚胺法将半抗原与载体蛋白偶联制备人工抗原,红外光谱法鉴定结果表明,人工抗原合成成功,基质辅助激光解析电离飞行时间质谱鉴定表明去甲氯胺酮半抗原与牛血清白蛋白的偶联比为11:1。经动物免疫,获得高效价特异性多克隆抗体,抗血清效价可达5.12×104。     

Stereodynamics and conformational chirality of the atropisomers of ditolyl anthrones and anthraquinone

Syn and anti conformers in similar proportions were observed at ambient temperature for the title compounds. The conformational assignment of the two anthrones was obtained by the observation of different multiplicity of the methylene NMR signals, whereas that of the anthraquinone derivative was determined by NOE experiments. The anti-to-syn interconversion barriers were obtained by line-shape simulation of the temperature-dependent NMR spectra, and by saturation transfer experiments. In one case the X-ray diffraction indicated that the syn is the only structure observed in the crystals.     

HPLC separation and fluorimetric estimation of chlorophylls and pheophytins in fresh and frozen peas

Summary A HPLC method for the separation and estimation of chlorophylls and pheophytins in fresh and frozen peas was assessed with the aim of following the colour changes of the products during storage under frozen conditions.The method involves the acetone extraction of the pigments, followed by HPLC on RP18 with isocratic elution by acetone: ethanol:water, (70:17:13), detecting and estimating the separated compounds by fluorimetry. The mobile phase composition was selected by monitoring the separation efficiency of several mixtures of solvents by HPLC. The reliability and the accuracy of the method were checked.     

1,3-Dipolar cycloadditions of silicon and tin alkynes and alkenes. Regiospecific synthesis of silyl and stannylpyrazoles and pyrazolines

Silicon and tin 3-, 3,5-, and 3,4,5-metalated pyrazoles have been synthesized by 1,3-dipolar cycloadditions of silyl-, disilyl-, and silylstannylacetylenes with N-phenylsydnone or trimethylsilyldiazomethane. On the other hand, 1- and 2-pyrazolines monometalated and dimetalated in different positions of the heterocycle have been prepared by reaction of vinylsilanes and vinylstannanes with the same 1,3-dipolar reagents. Other interesting products resulting from homologation were obtained by cycloaddition of trimethylsilyldiazomethane with β-silyl enones and esters. Moreover, for the first time a 3-silylpyrazole has been converted into a 3-cyanopyrazole.