Acetylation of alcohols with acetic anhydride promoted by N,N,N-trimethylanilinium tribromide

A wide variety of alcohols were reacted with acetic anhydride at room temperature in the presence of a catalytic amount of N,N,N-trimethylanilinium tribromide to produce the corresponding alkyl acetates in good to excellent yields. Following this procedure, acetylation of primary, secondary, and tertiary alcohols has been performed under neutral conditions.     

Inhibitive assessment of 1-(7-methyl-5-morpholin-4-yl-thiazolo[4,5-d]pyrimidin-2-yl)-hydrazine as a corrosion inhibitor for mild steel in sulfuric acid solution

In this study, the inhibitive effect of synthesized 1-(7-methyl-5-morpholin-4-yl-thiazolo[4,5-d]pyrimidin-2-yl)-hydrazine (MMTPH) as a new corrosion inhibitor for mild steel in 0.5 M sulfuric acid medium is investigated employing potentiodynamic polarization, electrochemical impedance spectroscopy and linear polarization resistance techniques. The results show MMTPH reduces anodic dissolution, retards the hydrogen evolution reaction and its adsorption follows Langmuir’s adsorption isotherm. Any increase in temperature will in turn increase corrosion current densities; however, the presence of MMTPH hinders the rate. In solutions with inhibitor concentration of 200 ppm, temperature elevations as great as 30° (25–55 °C) result in a drop of about 45 % in inhibition efficiency (99–55 %). Thermodynamic adsorption parameters show that the MMTPH is absorbed by a spontaneous exothermic process and the adsorption mechanism is physical. Quantum chemical method shows that the MMTPH molecules can be directly adsorbed at the steel surface on the basis of donor–acceptor interactions between π-electrons of pyrimidine, N atoms of hydrazine and vacant d-orbitals of iron atoms.     

Prolinium Triflate: a protic ionic liquid which acts as water-tolerant catalyst in the alkylation of indoles

Prolinium triflate (ProTf) was easily prepared by addition of triflic acid to an aqueous solution of l-proline. The latter is employed as a catalyst for the condensation of indoles with aldehydes or ketones in aqueous media to form a series of bisindolyl methanes in high yields.     

Proportional concentration phenomena on the sphere

In this paper we establish concentration phenomena for subspaces with arbitrary dimension. Namely, we display conditions under which the Haar measure on the sphere concentrates on a neighborhood of the intersection of the sphere with a subspace ofR ⁿ of a given dimension. We display applications to a problem of projections of points on the sphere, and to the duality of entropy numbers conjecture. Research was partially supported by the Israel Science Foundation.     

An efficient and green one-pot synthesis of tetrahydrobenzo[a]xanthenes, 1,8-dioxo-octahydroxanthenes and dibenzo[a,j]xanthenes by Fe3O4@Agar-Ag as nanocatalyst

Molecular Diversity - Agar-coated Fe3O4 nanoparticles (Fe3O4@agar) were prepared simply through in situ co-precipitation of Fe2+ and Fe3+ ions via NH4OH in an aqueous solution of Agar. Coating of...     

The role of folic acid in inducing of apoptosis by zinc(II) complex in ovary and cervix cancer cells

Molecular Diversity - Herein, the synthesis, structure, binding affinity, cytotoxicity, and apoptotic properties of the new Zn(II) complex composed of folic acid and bipyridine ligands are...     

Sulfamic acid immobilized on amino‐functionalized magnetic nanoparticles: A new and active magnetically recoverable catalyst for the synthesis of N‐heterocyclic compounds

Sulfamic acid immobilized on amino‐functionalized magnetic nanoparticles (MNPs/DETA‐SA) was successfully fabricated and characterized using various techniques. Diameters of approximately 15 nm for the MNPs/DETA‐SA were observed from scanning electron microscopy images. The as‐fabricated nanocomposite was applied as an efficient and magnetically reusable catalyst for the synthesis of 2,3‐dihydroquinazoline‐4(1H)‐one and polyhydroquinoline derivatives. All products were obtained in good to excellent yields. Recovery tests confirm that the catalyst can be readily recovered using an external magnet and reused many times without significant loss of its catalytic activity.     

Zirconium oxide complex‐functionalized MCM‐41 nanostructure: an efficient and reusable mesoporous catalyst for oxidation of sulfides and oxidative coupling of thiols using hydrogen peroxide

Zirconium oxide complex‐functionalized mesoporous MCM‐41 (Zr‐oxide@MCM‐41) as an efficient and reusable catalyst is reported for the oxidation of sulfides into sulfoxides using hydrogen peroxide (H₂O₂) as the oxidant, with short reaction times in good to excellent yields at room temperature under solvent‐free conditions. Also, a simple and efficient method is reported for the oxidative coupling of thiols into corresponding disulfides in good to high yields using H₂O₂ as oxidant in the presence of Zr‐oxide@MCM‐41 as recoverable catalyst in ethanol at room temperature. A series of sulfides and thiols possessing functional groups was successfully converted into corresponding products. After completion of reactions the catalyst was easily separated with simple filtration from the reaction mixture and reused for several consecutive runs without significant loss of catalytic efficiency. The mesoporous catalyst was characterized using Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface area measurements, X‐ray diffraction, transmission and scanning electron microscopies, energy‐dispersive X‐ray spectroscopy and thermogravimetric analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

First‐principle investigation of strain effects on the electronic properties of germanium nanowires

Using the GGA functional in density functional theory, the effects of axial strain on the band structure and effective mass of narrow [110] and [100] germanium nanowires are investigated. It is observed that both compressive and tensile strain cause indirect‐to‐direct bandgap transitions. One percent of tensile strain can cause a 40 meV change in the bandgap of [110] nanowires. Effective masses of electrons and holes are subject to a change of 3–4 times in the strain‐induced transition point. This change translates into a density of state modulation which opens new possibilities for the construction of Ge nanowire‐based sensors. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electrochemical Pseudocapacitors Based on Ternary Nanocomposite of Conductive Polymer/Graphene/Metal Oxide: An Introduction and Review to it in Recent Studies

This review gives an overview of the synthesis, surface and electrochemical investigations over ternary nanocomposite of conductive polymers in the development of new supercapacitors. They utilize both Faradaic and non‐Faradaic procedures to store charge, leading to higher specific capacitance and energy density, higher cell voltage, longer life cycle and moderated power density. Owing to a unique combination of features such as superb electrical conductivity, corrosion resistance in aqueous electrolytes, highly modifiable nanostructures, long cycle life and the large theoretical specific‐surface area, the use of ternary nanocomposites as a supercapacitor electrode material has become the focus of a significant amount of current scientific researches in the field of energy storage devices. In these nanocomposites, graphene not only can be utilized to provide a substrate for growing nanostructured polymers in a polymer‐carbon nanocomposite structure in order to overcome the insulating nature of conductive polymers at dedoped states, but also is capable of providing a platform for the decoration of metal oxide nanoparticles to avoid their agglomeration. In this regard, synthesis, characterization and performance of different ternary nanocomposites of conductive polymer/graphene/metal oxide are discussed in detail. These remarkable results demonstrate the exciting commercial potential for high performance, environmentally friendly and low‐cost electrical energy storage devices based on ternary nanocomposite of conductive polymer/graphene/metal oxide.