Oxidative amidation of benzyl alcohol,benzaldhyde, benzoic acid styrene and phenyl acetylene catalyzed by ordered mesoporous HKUST‐1‐Cu: Effect of surface area on oxidative amidation reaction

HKUST‐1‐Cu synthesized in the presence and absence of P‐123 trough solvotermal method. After characterization using some different microscopic and spectroscopic techniques such as XRD, FT‐IR, SEM, ICP, BET and TEM its catalytic activity was investigated in the oxidative coupling of benzyl alcohol, benzaldhyde, benzoic acid, styrene and phenyl acetylene with N,N‐dialkylformamides for the preparation of N,N‐dimethylformamides. Different derivatives of tertiary amides were synthesized in moderate to good yields in the presence of just ~0.28 mol% of this catalytic system. Reusability of the synthesized catalysts was examined and catalysts were reusable for 8 times without significant decrease in optimized conditions.     

Dendrimer-encapsulated copper(II) immobilized on Fe3O4@SiO2 NPs: a robust recoverable catalyst for click synthesis of 1,2,3-triazole derivatives in water under mild conditions

Research on Chemical Intermediates - In this paper, we have introduced Fe3O4@SiO2-dendrimer-encapsulated Cu(II) as a heterogeneous reusable catalyst for Cu-catalyzed azide-alkyne cycloaddition...     

Global dynamics of an epidemiological model with age-of-infection dependent treatment rate

We revisit a previously established model for influenza transmission dynamics, in which antiviral treatment as a single containment strategy was administered within a specified window of opportunity for initiating treatment. We extend this model to a more general framework with age-of-infection dependent treatment rates. The resulting age structured model can be transformed into a closed system of delay differential equations, for which we perform a complete global stability analysis. By constructing suitable Lyapunov functions, we show that the effective reproduction number fully characterizes the possible outcomes of disease dynamics. Our results allow us to evaluate treatment strategies and examine the impact of treatment delays on the potential success of disease control.     

Solvent-Free Conditions as an Eco-Friendly Strategy for Synthesis of Organophosphorus Compounds

A series of diverse NH- and CH-acids are used for a one-pot synthesis of stable phosphorus ylides and 1,4-diionic organophosphorus compounds by trapping of the zwitterionic intermediate from the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates under solvent-free conditions. The structural geometry for one of the products was confirmed by single crystal X-ray diffraction analysis.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Copper,gold, and silver decorated magnetic core–polymeric shell nanostructures for destruction of pathogenic bacteria

Fe₃O₄ magnetic nanoparticles (MNPs) were prepared by co-precipitation method. The nanoparticles were silica coated using TEOS, and then modified by the polymeric layers of polypropylene glycol (PPG) and polyethylene glycol (PEG). Finally, the core-shell samples were decorated with Ag, Au, and Cu nanoparticles. The products were characterized by vibrating sample magnetometry (VSM), TGA, SEM, XRD, and FTIR methods. The antibacterial activity of the prepared samples was evaluated in inactivation of E. coli and S. aureus microorganisms, representing the Gram-negative and Gram-positive species, respectively. The effect of solid dosage, bacteria concentration and type of polymeric modifier on the antibacterial activity was investigated. TEM images of the bacteria were recorded after the treatment time and according to the observed changes in the cell wall, the mechanism of antibacterial action was discussed. The prepared nanostructures showed high antibacterial activity against both Gram-negative and Gram-positive bacteria. This was due to the leaching of metal ions which subsequently led to the lysis of bacteria. A theoretical investigation was also done by studying the interaction of loaded metals with the nucleotide components of the microorganism DNA, and the obtained results were used to explain the experimental data. Finally, based on the observed inactivation curves, we explain the antibacterial behavior of the prepared nanostructures mathematically.

     

Synthesis of Flexible Elastomeric Polyurethane Films with High Elasticity and Evaluation of Their Structural Permanency

Flexible elastomeric polyurethane (EPU) films were synthesized by ultraviolet (UV) curing of thermoplastic polyurethanes (TPUs) through the reaction among poly (oxytetramethylene) diol (PTMO), isophorone diisocyanate (IPDI), cis-2-butene-1,4-diol (cis-BDO), and 1,6-hexanediol diacrylate (HDDA). In order to improve elasticity and structural permanency in the synthesized TPUs, cross-linking reaction involving unsaturated groups of chain extender (cis-BDO) and reactive diluent (HDDA) using 27 and 41 seconds of UV radiation is introduced. Investigation of structure and mechanical properties was performed using FTIR, GPC, and tensile tests. Stress-strain behavior showed that Young's moduli of EPUs were in the range of 0.2 to 0.4 MPa, which is evidence for high flexibility. Three times of repeated loading on one sample up to 100% strain with 10 min intervals for its recovery showed that considerable structural change didn't occur under these conditions and all observed permanent sets vanished within a time not exceeding 10 min.     

H2SO4O2 AS AN EFFICIENT CATALYST FOR THE PREPARATION OF PHENYLHYDRAZONES AND 2,4-DINITROPHENYLHYDRAZONES UNDER SOLVENT-FREE CONDITIONS

HSO mixed with silica gel (1:1) by weight produces a white powder which is an effective catalyst for the conversion of carbonyl compounds to their corresponding phenylhydrazones and 2,4-dintrophenylhydrazones under solvent-free conditions.     

Gaseous Nitrogen Dioxide for Sustainable Oxidative Deprotection of Trimethylsilyl Ethers

Abstract

In this study, trialkylsilyl ethers of indispensable protected alcohols are oxidatively deprotected in neat form with gaseous nitrogen dioxide (NO₂). Quantitative yields of aldehydes or ketones are obtained without the necessity of chromatography. The byproducts, nitrogen monoxide, anhydrous nitric acid, and hexamethyldisiloxane, can be quantitatively separated by evaporation and distillation in closed systems for recycling or further use. The direct new method supersedes the previous techniques that produce dangerous wastes and require chromatographic workup, while the atmospheric gas NO₂ and its gaseous reduction products are easily kept in closed systems until further use.     

A VERSATILE METHOD FOR THE CONVERSION OF ALDOXIMES TO NITRILES USING SILICA GEL/THIONYL CHLORIDE

A simple convenient procedure for dehydration of aldoximes has been developed using silica gel/thionyl chloride in heterogeneous conditions. The method has been found to be effective for a wide range of aromatic oximes.