Dynamic heat and moisture transfer in bulky PAN nanofiber mats

In this study a non-conventional electrospinning technique was designed for the production of high bulky polyacrylonitrile (PAN) nanofiber mats. Optimum nanofiber mats are achieved with 15 wt.% solution of PAN in dimethylformamide. Such mats result in a bulk porosity which is as high as 99.9 and a density as low as 0.84 × 10⁻³ g/cm³. The effect of the porosity of nanofiber mats on the air permeability and coupled heat and moisture transfer of fibers was investigated. Based on the results, high bulky nanofiber mats possess high heat and moisture transfer. Experimental data reveal that upon a slight decrease in the bulk porosity, air permeability and heat transfer decrease noticeably, while moisture transfer variation is low.     

Synthesis,characterization and application of nano-N,N,N′,N′-tetramethyl-N-(silica-n-propyl)-N′-sulfo-ethane-1,2-diaminium chloride as a highly efficient catalyst for the preparation of N,N′-alkylidene bisamides

Research on Chemical Intermediates - A novel mesoporous nanomaterial, namely nano-N,N,N′,N′-tetramethyl-N-(silica-n-propyl)-N′-sulfo-ethane-1,2-diaminium chloride...     

Pyrazinium Di(hydrogen sulfate) as a Novel,Highly Efficient and Homogeneous Catalyst for the Condensation of Enolizable Ketones with Aldehydes,Acetonitrile and Acetyl Chloride

A highly efficient protocol for the synthesis of β‐acetamido ketone or ester derivatives in the presence of pyrazinium di(hydrogen sulfate) {Py(OSO₃H)₂} as a novel, green and homogeneous solid acid catalyst at room temperature is described. One‐pot multi‐component condensation of enolizable ketones or alkyl acetoacetates with aldehydes, acetonitrile and acetyl chloride affords the title compounds in high to excellent yields and in relatively short reaction times. In this work, the efficiency of our recently reported solid acid catalyst, saccharin sulfonic acid (Sa‐SO₃H), in the synthesis of β‐acetamido ketones/esters is also studied. Moreover, in this research, some new β‐acetamido ketones and esters (i.e. one complex structure) are prepared.     

Copper Oxide Nanoparticle Modified Sol–Gel‐Derived Carbon Ceramic by Microwave Irradiation,and Its Application for Determination of Adenine at Very Low Potential

In this work the copper oxide nanoparticles simultaneous with sol–gel‐derived carbon ceramic production were synthesized and doped in ceramic by microwave irradiation in a few minutes without using any catalyst and organic solvent. The ceramic composition was characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS) and Fourier transforms infrared (FT‐IR), and its surface morphology was investigated by scanning electron microscopy (SEM). The proposed ceramic with detection limit of 0.1 µM, was used for electrocatalytic determination of adenine at potential about 700 mV lower than its usual oxidation potential.     

Silica sulfuric acid as mild and efficient catalyst for the preparation of poly-hydroxyl aromatic compounds under mild and heterogeneous conditions

A simple, clean and highly efficient method for the preparation of polyhydroxyl aromatic compounds is described from the reaction of 2,6-bis(methylol)phenols and different substituted phenols in the presence of silica sulfuric acid (SSA) as a heterogeneous catalyst. SSA afforded the clean synthesis of target compounds in much higher yields than traditional catalysts. The established method is also suitable for the synthesis of phloroglucinol derivatives (Phloroglucides) and other polyhydric phenols. Besides the easy work-up of the reaction mixture, the comfortable purification of the products is another advantage of this method.     

Preparation,characterization and utilization of a novel dicationic molten salt as catalyst for the synthesis of bis(6-amino-1,3-dimethyluracil-5-yl)methanes

Research on Chemical Intermediates - In this research, firstly, preparation and characterization of a novel dicationic molten salt, namely N,N,N′,N′-tetramethylethylenediaminium...     

Efficient method for the direct preparation of amides from carboxylic acids using tosyl chloride under solvent-free conditions

A simple, clean and highly efficient solvent-free procedure for the preparation of primary, secondary, tertiary and aromatic amides is described from the direct reaction of carboxylic acids and silica-supported ammonium salts, triethylamine (TEA) and tosyl chloride (TsCl) as condensing agent. The reaction proceeds rapidly in high yields at room temperature.     

A simple and selective sensor for the determination of ascorbic Acid in vitamin C tablets based on paptode.

A method for the determination of ascorbic acid in vitamin C tablets based on a very simple paptode design on TLC strips is described. This procedure is based on the reduction of iron(III) with ascorbic acid and the formation of a colorful red complex with immobilized 2,2'-dipyridyl (dipy) on TLC strips. The linear range of the system was 20-200 ppm with a detection limit of 1 ppm and a relative standard deviation of 1.5% (n = 28). The parameters, such as pH, concentration of iron(III), concentration of dipy and the volume of dipy per 1 cm(2) of TLC strips, were optimized. The proposed sensor was successfully applied for the determination of ascorbic acid in vitamin C tablets.     

Regioselective N‐Arylation of Some Pyrimidine and Purine Nucleobases

N‐Arylation of some pyrimidine and purine nucleobases in the presence of SiO₂ and Cs₂CO₃ under solvent‐free as well as in solution conditions is described. In these conditions, N1‐aryl pyrimidines and N9‐aryl purines have been obtained regioselectively in moderate to high yields with relatively short reaction times.     

Green,Catalyst-Free Protocol for the Efficient Synthesis of N-Sulfonyl Aldimines and Ketimines in Ionic Liquid [Bmim]Br

Sulfonamides are efficiently condensed with aldehydes as well as ketones in the absence of catalyst in 1-butyl-3-methylimidazolium bromide ([bmim]Br) under microwave irradiation to afford N-sulfonyl aldimines and ketimines in good to excellent yields in short reaction times.