Highly efficient transition metal-free coupling of acid chlorides with terminal alkynes in [bmim]Br: A rapid route to access ynones using MgCl2

A simple, mild, highly efficient and transition metal-free protocol for synthesis of ynones in an ionic liquid is described. In this approach, the coupling reaction of different acid chlorides with terminal alkynes was efficiently carried out using 0.05 mol% MgCl₂ in the presence of triethylamine in [bmim]Br at room temperature to afford the corresponding ynones in good to excellent yields. This method is highly efficient for various acid chlorides and alkynes including aliphatic, aromatic, and heteroaromatic substrates bearing different functional groups. The influence of some parameters in this reaction including type of ionic liquid, base and catalyst has been discussed.     

New development of synthesis and reactivity of seleno- and tellurophenes

Due to the many new and remarkable findings and applications that have been published in recent years in seleno- and tellurophene chemistry, this review revisits the different aspects of this chemistry, including synthesis, reactivity and applications in the field of heterocycles.     

Recent advances in synthesis of 2-pyridones: a key heterocycle is revisited

Owing to the versatile applications in different areas including biology, natural compounds, dyes, and fluorescent materials, the synthesis of 2-pyridone compounds is an important research field and has attracted a great deal of attention. In this review, 2-pyridones new synthetic methods are classified to tree classes including reactions based on pyridine rings, cyclization, and cycloaddition reactions.     

Determination of the molecular distribution in anisotropic media by polarized absorption and emission spectroscopy

A theory for the interpretation of polarized absorption and emission spectra of uniaxially oriented samples, including overlap of different polarized transitions in both processes, is described. Using this method for the interpretation of experimental data, the distribution of molecules possessing different geometrical anisotropy, incorporated in stretched polyethylene films, and the partial contribution of different polarized transitions to the total emission intensity can be estimated.     

标准物质基体对马拉硫磷气相色谱响应的影响

对马拉硫磷在甲醇、丙酮、乙酸乙酯、二氯甲烷4种溶剂中的气相色谱峰单位浓度面积响应进行了研究,用t检验法判定响应差异性.研究结果证明,浓度相同但溶剂不同的马拉硫磷溶液,在其它实验条件均相同的情况下,气相色谱峰单位浓度面积响应有显著性差异;用前处理后待测样浓缩液的基体稀释对照样,可以减小或消除马拉硫磷标准物质基体与方法中要求的标准储备液基体的差异性所带来的对待测样检测结果的影响.     

Control on Crystal Forms of Ultrafine Barium Carbonate Particles and Study on its Mechanism

1 INTRODUCTION Barium carbonate is one of the important che- mical materials as well as one of the most important barium salts. Its application covers multitudinous in- dustries and fields such as building material, meta- llurgy, electron, chemical industry and so on[1]. With the fast development of science and technology, it is becoming more and more demanding with barium carbonate’s quality, and more and more scientific workers do researches on the control of Barium car- bonate’s crys…     

Quality evaluation of tandem mass spectral libraries

Tandem mass spectral libraries are gaining more and more importance for the identification of unknowns in different fields of research, including metabolomics, forensics, toxicology, and environmental analysis. Particularly, the recent invention of reliable, robust, and transferable libraries has increased the general acceptance of these tools. Herein, we report on results obtained from thorough evaluation of the match reliabilities of two tandem mass spectral libraries: the MSforID library established by the Oberacher group in Innsbruck and the Weinmann library established by the Weinmann group in Freiburg. Three different experiments were performed: (1) Spectra of the libraries were searched against their corresponding library after excluding either this single compound-specific spectrum or all compound-specific spectra prior to searching; (2) the libraries were searched against each other using either library as reference set or sample set; (3) spectra acquired on different mass spectrometric instruments were matched to both libraries. Almost 13,000 tandem mass spectra were included in this study. The MSforID search algorithm was used for spectral matching. Statistical evaluation of the library search results revealed that principally both libraries enable the sensitive and specific identification of compounds. Due to higher mass accuracy of the QqTOF compared with the QTrap instrument, matches to the MSforID library were more reliable when comparing spectra with both libraries. Furthermore, only the MSforID library was shown to be efficiently transferable to different kinds of tandem mass spectrometers, including “tandem-in-time” instruments; this is due to the coverage of a large range of different collision energy settings—including the very low range—which is an outstanding characteristics of the MSforID library.     

Comparison on the antioxidant capacity of selected fruits and vegetables and their separations

Several kinds of fruits, including apple, pear, and grape, and vegetables, including onion and tomato, were studied in this paper. FRAP and DPPH assays were used to determine the antioxidant activity of ethanol extracts and their separations. After being extracted, different phenolic compounds were separated on Sephadex LH-20 column. EC1 and EC50 were used to show the ferric reducing ability and DPPH scavenging activity. The results indicated that the Fe-reducing ability order of different extracts was different with that of DPPH scavenging ability. The mutual effect of the substances in the mixture influenced the antioxidant activity of the separations. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 333–335, July–August, 2006.     

果糖脱水制备5-羟甲基糠醛

5-羟甲基糠醛(HMF)是一种重要的生物基材料单体,具有非常广泛的应用价值。果糖等己糖选择性脱水是制备5-羟甲基糠醛的主要方法之一。本文首先从催化剂的角度出发,介绍了近年来不同均相和多相酸性催化剂在该反应中的应用。按照反应溶剂体系进行分类,总结了近年来该领域中不同溶剂体系的研究进展,包括双相溶剂体系、亚/超临界流体溶剂体系和离子液体溶剂体系等。最后,指出了新型多相酸性催化剂以及高效溶剂体系的开发和改进是该领域将来主要的研究方向。     

Low-Temperature Plasma Treatment as an Effective Method for Surface Modification of Polymeric Materials

The specific features of the plasma modification process and its application area are considered. It is shown that this method is very effective for the enhancement of adhesive properties of a wide range of polymeric materials used in different fields of technology, as well as in the manufacture of membranes for different designations, including membranes for biological and medical purposes.     

污水厂污泥堆肥后重金属形态变化分析

采用高温好氧静态强制通风堆肥工艺,研究了污水厂污泥与稻草、锯末、粉煤灰、磷矿粉、石灰按不同比例混合堆肥前后重金属在交换态、碳酸盐结合态、铁锰氧化物结合态3种不稳定态和包括有机结合态、残渣态的稳定态含量的变化。结果表明,该试验可以显著降低污泥中交换态Cu、Pb、Zn、Cd和As的含量,提高其它形态的含量。由此可见,堆肥处理可以在一定程度上降低重金属活性并保持养分,从而达到农业利用的目的。     

Liquid chromatography/mass spectrometry for investigating the biochemical effects induced by aristolochic acid in rats: the plasma metabolome

In this study, high‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry in conjunction with chemometric methods including principal components analysis was used to investigate metabolic profiling in plasma samples from rats dosed with aristolochic acid (AA). Differentiating metabolites were identified by high‐resolution mass spectrometry and tandem mass spectrometry analyses, database searching and comparison with the analytical results of authentic standards. Several metabolites in plasma including a glucuronide conjugate, bile acids, lysophosphatidylcholines and fatty acids were detected in rats exposed to AA. To improve visualization, a z‐score plot and a cluster heat map were generated for the concentration fluctuations of the metabolites in different dosage groups. The results obtained from this study indicated that class‐specific metabolomic patterns were obviously differentiated for each metabolite in the different dosage groups of AA. Copyright © 2010 John Wiley & Sons, Ltd.     

Electrochemical dating: a review

The suitability of electrochemical methods for dating archaeological materials is discussed on the basis of the general requirements for defining ‘electrochemical clocks’. Solid state electrochemistry methods have been proposed for dating different archaeological materials including ceramic and glasses and different metals and alloys. The state of the art on this matter and future expansion of this methodology is discussed.     

Preparation and characterization of the inclusion complex of Ofloxacin with ��-CD and HP-��-CD

The formation of the inclusion complexes of Ofloxacin with cyclodextrins (CDs) including ??-cyclodextrin (??-CD), and hydroxypropyl-??-cyclodextrin (HP-??-CD) were studied by Fluorescence, UV?CVis absorption spectroscopy and nuclear magnetic resonance spectroscopy (NMR) in solution. Experimental conditions including the concentration of various CDs and media acidity were investigated in detail at room temperature. The results suggested that in different pH solutions, CDs have different inclusive capacity to different forms Ofloxacin. ??-CD was most suitable for inclusion of neutral form and HP-??-CD was suitable for acidic form. The binding constant (K) of the inclusion complex was determined by fluorescence measurement, and the complexation ratio was determined as 1:1 in the concentration range used in this study. A mechanism was proposed to explain the inclusion process based on the experimental NMR data.     

Electrochemical investigations of the various electrolytes for high energy density metal oxide supercapacitor

Journal of Solid State Electrochemistry - In this work, the asymmetric supercapacitor (ASC) devices with three different electrolytes including aqueous, organic, and gel polymer electrolytes have...     

The importance of nuclear analytical techniques in the determination of mineral micronutrients in Iranian daily diets

This article explains the application of a few nuclear and non nuclearanalytical techniques to determine a number of toxic and essential trace elementsin human daily intakes. The diets are the food patterns of different populationof Iranian provinces with different food habits.In this article a comparisonhas been made for mineral micronutrient intaken by the different populationvia the pattern of nutrients in their daily diets. In the meantime resultingoutcome from different analytical techniques including instrumental and radiochemicalneutron activation analysis have been compared and discussed.     

Recent advances in [2+2+2] cycloaddition reactions

The [2+2+2] cycloaddition is an elegant, atom-efficient and group tolerant process for the synthesis of carbo- and heterocycles, mostly aromatic, involving the formation of several C-C bonds in a single step. Cyclotrimerisation is catalyzed by a variety of organometallic complexes, including more than 15 different metals. The aim of this tutorial review is to point out the most recent advances in this field and to encourage the use of this reaction enroute to complex molecules. After summarizing the most common catalysts and reaction conditions generally used, we survey the mechanistic features currently accepted for this reaction. Section 4 covers the scope of the different [2+2+2] cycloaddition versions starting with the cyclotrimerisation of three triple bonds, including nitriles, with especial emphasis on asymmetric reactions that create central, axial or planar chirality. Then, reactions that use double bonds are addressed. Finally, the most outstanding examples of natural products synthesis using [2+2+2] cycloadditions as a key step reported recently are shown.     

On-line sample concentration techniques in capillary electrophoresis: velocity gradient techniques and sample concentration techniques for biomolecules

Methods with a high sensitivity and high separation efficiency are goals in analytical separation techniques. On-line sample concentration techniques in capillary electrophoresis (CE) separations have rapidly grown in popularity over the past few years because they achieve this goal. This review describes the methodology and theory associated with a number of different techniques, including electrokinetic and chromatographic methods. For small molecules, several on-line concentration methods based on velocity gradient techniques are described, in which the electrophoretic velocities of the analyte molecules are manipulated by field amplification, sweeping, and isotachophoretic migration, resulting in the on-line concentration of the analyte zones. In addition, the on-line concentration methods for macromolecules are described, since the techniques used for macromolecules (DNAs and proteins), are different from those for small molecules, with respect to either mechanism or methodology. Recent studies relating to this topic are also discussed, including electrophoretic and chromatographic techniques on capillary or microchip.     

手性2-甲基哌嗪的制备

手性2_甲基哌嗪在有机合成中有着广阔的应用前景。本文从手性试剂拆分、利用手性原料制备及构建手性中心等方面,对手性2_甲基哌嗪的制备过程进行了介绍并评价了各种路线的可行性和适用性。