以蛋壳为原料制备的纳米氧化钙用于高效催化合成吡喃并[4,3-b]吡喃(英文)

Nano-CaO was prepared by calcination of ball-milled chicken eggshell waste.This novel,bioactive,heterogeneous catalyst,which had high catalytic activity and reusability,was used in the green synthesis of pyrano[4,3-b]pyrans via condensation of various aromatic aldehydes,malononitrile,and 4-hydroxy-6-methyl-2H-pyran-2-one at 120 °C under solvent-free conditions.The reaction proceeded to completion within 5–45 min in 93%–98% yield.The nano-CaO was fully characterized by scanning electron microscopy,X-ray powder diffraction,infrared spectroscopy,X-ray fluorescence spectroscopy,and thermal gravimetric,surface area,and elemental analyses.     

Preparation and characterization of optically active and organosoluble poly(amide‐imide)s from polycondensation reaction of N,N′‐(4,4′‐sulphonediphthaloyl)‐bis‐L‐isoleucine diacid with aromatic diamines

3,3′,4,4′‐Diphenylsulfonetetracarboxylic dianhydride (1) was reacted with L ‐isoleucine (2) in acetic acid and the resulting imide‐acid (3) was obtained in high yield. The diacid chloride (4) was prepared from the diacid derivative (3) by reaction with thionyl chloride. The polycondensation reaction of diacid chloride (4) with several aromatic diamines such as 4,4′‐sulfonyldianiline (5a), 4,4′‐diaminodiphenyl methane (5b), 4,4′‐diaminodiphenylether (5c), p‐phenylenediamine (5d),m‐phenylenediamine (5e), 2,4‐diaminotoluene (5f) and 4,4′‐diaminobiphenyl (5g) was performed by two conventional methods: low temperature solution polycondensation and short period reflux conditions. In order to compare conventional solution polycondensation reaction methods with microwave‐assisted polycondensation, the reactions were also carried out under microwave conditions with a small amount of o‐cresol that acts as a primary microwave absorber. The reaction mixture was irradiated for 6 min with 100% of radiation power. Several new optically active poly(amide‐imide)s with inherent viscosity ranging from 0.23 to 0.41 dl/g were obtained with high yield. All of the earlier polymers were fully characterized by IR, elemental analyses and specific rotation techniques. Some structural characterizations and physical properties of these new optically active poly(amide‐imide)s are reported. Copyright © 2005 John Wiley & Sons, Ltd.     

Graphitic carbon nitride embedded hydrogels for enhanced gel electrophoresis

Here, we show, for the first time, the use of graphitic carbon nitride (g-C₃N₄) nanosheets to improve the resolution and efficiency of protein separation in gel electrophoresis. By loading 0.04% (m/v) g-C₃N₄ nanosheets into the polyacrylamide gel at 25 °C, the thermal conductivity increased approximately 80% which resulted in 20% reduction in Joule heating and overall increase of separation efficiency. Also, polymerization of acrylamide occurred in the absence of tetramethylethylenediamine (TEMED) when the polyacrylamide gel contained g-C₃N₄ nanosheets. Hence, the g-C₃N₄ act simultaneously as a polymerization catalyst as well as heat sinks to lower Joule heating effect on band broadening.     

A facile one-pot synthesis of functionalized thiazines in water

An efficient synthesis of thiazines from the three component reactions between dialkyl acetylenedicarboxylates,arylisothio-cyanates and iV-nucleophiles at room temperature in water as the solvent is described.     

Silver nanoparticles plasmon resonance-based method for the determination of uric acid in human plasma and urine samples

We have developed a simple and sensitive colorimetric procedure for the quantification of trace amounts of uric acid. It is based on the finding that uric acid in a medium containing ammonia and sodium hydroxide at 65?°C can reduce silver ions to form yellow silver nanoparticles (Ag NPs). These are stabilized in solution by using poly(vinyl alcohol) as a capping agent. The yellow color of the solution that results from the localized surface plasmon resonance of Ag NPs can be observed by the bare eye. The absorbance at 415?nm is proportional to the concentration of uric acid which therefore can be determined quantitatively. The calibration curve is linear in the concentration range from 10 to 200?nM, with a limit of detection of 3.3?nM. The method was successfully applied to the determination of uric acid in human plasma and urine samples.

Recent advances in application of intramolecular Suzuki cross-coupling in cyclization and heterocyclization

Abstract  

Palladium-catalyzed reactions are key steps for the formation of carbon–carbon bonds in modern synthetic chemistry and among these reactions few have influenced organic synthesis as greatly as the Suzuki–Miyaura reaction which was first reported in 1979. This review highlights recent and major developments of this approach in intramolecular cyclization and heterocyclization reactions.     

<Emphasis Type="Italic">N</Emphasis>-Bromo Reagent Mediated Oxidation of Urazoles to Their Corresponding Triazolinediones under Mild and Heterogeneous Conditions

Summary. Various N-bromo reagents [HMTAB, DABCO-bromine, DPTBE, and TBCA] were used as effective oxidizing agents for the oxidation of urazoles and bisurazoles to their corresponding triazolinediones under mild and heterogeneous conditions at room temperature with good to excellent yields. Also the oxidation of some new 4-phenylurazole derivatives with these reagents is discussed.     

An Efficient Method for Chemoselective Reduction of Nitro Compounds Using Bimetallic Fe‐Ni NPs/H3PW12O40.×H2O System

The selective reduction of nitro compounds by treatment with bimetallic Fe‐Ni nanoparticles (NPs) and tungestophosphoric acid hydrate (H₃PW₁₂O₄₀.×H₂O) in H₂O is reported. The method has been applied to a broad range of nitro compounds with different sensitive functionalities, including halides, carbonyl, hydroxyl, aldehyde, methyl, acetyl, nitrile, and ester substituents with excellent yields. The reaction yielded single product in all cases with very high yield. The simple experimental procedure and easy purification make the protocol advantageous.