A New Convenient Laboratory Synthesis of Trimethylsilyl Bromide

Trimethylsilyl bromide is prepared in a laboratory scale from trimethylsilyl 4-bromo 2-alkenoates in almost quantitative yield.     

Complexes of Low Oxidized 99Tc and Re with Thiosalicylic Acid and Their Characterization in Solution with Some CNDO-MO Calculations

Complexation of technetium-99 and rhenium in low oxidized forms with thiosalicylic acid (TSA) were investigated by uv.-vis. spectrophotometry and HPL-chromatography.

By CNDO-MO calculations of the proper structure of TSA, the charge densities, ionization potential, electron affinity and its dipole moment were studied. The violet solútions of the Tc and Re complexes exhibit characteristic bands in the visible at 420,590 nm and 410,570 nm respectively. Comparative HPLC studies using MeOH/H₂O as a mobile phase indicate the Re-TSA complex to be less stable than the Tc-TSA complex.     

Electrochemical behavior of aluminum and some of its alloys in chloroaluminate ionic liquids: electrolytic extraction and electrorefining

The electrochemical behaviors of pure Al, Al–6%Si, Al–3%Cu, and Al–3.7%Cu–0.9%Mg–0.8%Pb–0.6%Fe alloys were investigated in the chloroaluminate ionic liquids 1-butyl-3-methylimidazolium chloride [BMIm]Cl/AlCl₃ (40/60 mol%) and 1-ethyl-3-methylimidazolium chloride [EMIm]Cl/AlCl₃ (40/60 mol%). Electrolytic extraction of copper from Al–Cu alloys in the employed ionic liquids was explored. The alloys were anodically dissolved in the ionic liquids and then pure copper was recovered under potentiostatic conditions. Due to the large difference between the deposition potentials of Cu and Al, pure Cu can be obtained without Al contamination. Electrorefining of Al–3%Cu and Al–6%Si alloys was also investigated in [BMIm]Cl/AlCl₃ (40/60 mol%) at room temperature. High purity aluminum deposits were obtained with significantly low energy consumption of about 2 kWh/kg of Al.     

New eco-friendly animal bone meal catalysts for preparation of chalcones and aza-michael adducts

ABSTRACT: Two efficient reactions were successfully carried out using Animal Bone Meal (ABM) and potassium fluoride or sodium nitrate doped ABMs as new heterogeneous catalysts under very mild conditions. After preparation and characterization of the catalysts, we first report their use in a simple and convenient synthesis of various chalcones by Claisen-Schmidt condensation and then in an aza-Michael addition involving several synthesized chalcones with aromatic amines. All the reactions were carried out at room temperature in methanol; the chalcone synthesis was also achieved in water environment under microwave irradiation. Doping ABM enhances the rate and yield at each reaction. Catalytic activities are discussed and the ability to re-use the ABM is demonstrated. RESULTS: For Claisen-Schmidt the use of ABM alone, yields never exceeded 17%. In each entry, KF/ABM and NaNO3/ABM (79-97%) gave higher yields than using ABM alone under thermic condition. Also the reaction proceeded under microwave irradiation in good yields (72-94% for KF/ABM and 81-97% for NaNO3/ABM) and high purity. For aza-Michael addition the use of ABM doped with KF or NaNO3 increased the catalytic activity remarkably. The very high yields could be noted (84-95% for KF/ABM and 81-94% for NaNO3/ABM). CONCLUSION: The present method is an efficient and selective procedure for the synthesis of chalcones anaaza-Michael adducts. The ABM and doped ABMs are a new, inexpensive and attractive solid supports which can contribute to the development of catalytic processes and reduced environmental problems.     

State space approach to magnetohydrodynamic flow of perfectly conducting micropolar fluid with stretch

In this work we introduce a model of the boundary layer equations for a perfect conducting micropolar fluid with stretch, bounded by an infinite vertical flat plane surface of a constant temperature. This model is applied to study the effects of free convection currents on the flow of the fluid in the presence of a constant magnetic field. The state space technique is adopted for the solution of a one‐dimensional problem for any set of boundary conditions. The resulting formulation together with the Laplace transform techniques are applied to a thermal shock problem. The inversion of the Laplace transforms is carried out using a numerical approach. Numerical results are given and illustrated graphically for the problem. Copyright © 2011 John Wiley & Sons, Ltd.     

EPR on Medically Relevant NO Adsorbed to Zn-LTA

For medical purposes, materials are required that store and target specifically deliver exogenous nitric oxide (NO). Partially zinc-exchanged Na-LTA (Linde type A) zeolite (Zn-LTA) has high potential in this respect due to its non-toxicity and adsorption capacity for NO. In contrast to NO adsorbed to LTA zeolites prepared for catalytic purposes, lower dehydration temperature prior to NO adsorption is used to achieve a balance between production cost and high activity. In order to study the interaction of NO with the metal sites in the samples prepared under these medical conditions, continuous-wave X-band electron paramagnetic resonance has been applied. In contrast to Na-LTA with only one weakly interacting NO monomer, three different monomers, having stronger interaction to the metal sites than in Na-LTA, were observed in Zn-LTA. To improve the storage capacity of Zn-LTA, higher dehydration temperatures would be necessary.     

Chemical Preparation,Thermal Behavior,Kinetic, and IR Studies of MnK4(P3O9)2.2H2O,Crystallographic Data of a New Cyclotriphosphate MnK4(P3O9)2, and Quantum Chemical Calculations for the P3O3− 9 Ion

Abstract

Chemical presparation, thermal behavior, and infrared (IR) studies are discussed for the cyclotriphosphate MnK₄(P₃O₉)₂.2H₂O and its anhydrous form MnK₄(P₃O₉)₂. The total dehydration of MnK₄(P₃O₉)₂.2H₂O, between 200 and 550 °C, leads to its anhydrous form MnK₄(P₃O₉)₂. MnK₄(P₃O₉)₂ is a new cyclotriphosphate crystallizing in the rhombohedral system and is stable until its melting point at 560 °C. The thermal behavior of MnK₄(P₃O₉)₂.2H₂O has been investigated and interpreted by comparison with IR absorption spectrometry and X-ray diffraction experiments. Two different methods, Ozawa and KAS (Kissinger-Akahira-Sunose), were selected in studying the kinetics of thermal behavior of the title compound. Quantum chemical calculations were made for the P₃O ^3? ₉ ion.

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.

GRAPHICAL ABSTRACT     

Polyazomethines Bearing Furan Moieties. Solution Polycondensation of Bis(furanic diamine)s and Aromatic Dialdehydes

A series of new polyazomethines containing furan moieties was synthesized by polycondensation of bifuranic diamine monomers with commercially available aromatic dialdehydes viz., terephthaldehyde (TPA), isophthaldehyde (IPA). Inherent viscosities and number average molecular weights of polyazomethines were in the range 0.90–1.56 dL/g and 10460–17850 (SEC, polystyrene standard), respectively indicating formation of medium to reasonably high molecular weight polymers. The resulting polyazomethines were characterized by solubility tests, viscosity measurements, FTIR, NMR, UV spectroscopy, differential scanning calorimetric (DSC), and thermogravimetric analysis (TGA). These furan-based polyazomethines were essentially amorphous and exhibited glass transition temperatures (Tg) in the 150–190°C range. The temperature at 10% wt loss (T₁₀), determined from TGA of polyazomethines were in the range 300–380°C, indicating their good thermal stability.     

Dapson in Heterocyclic Chemistry,Part III: Synthesis,Antimicrobial, and Antitumor Activities of Some New Bisheterocyclic Compounds Containing Biologically Active Diphenylsulfone Moiety

The key intermediate diisothiocyanate 2 was allowed to react with 5-amino-3-methyl-pyrazole-4-carbonitrile 3, ethyl 5-amino-1-phenyl-pyrazole-4-carboxylate 6, 2-amino-tetrahydrobenzo[b]thiophene-3-car-bonitrile 9, ethyl-2-amino-tetra-hydrobenzo[b]thiophene-3-carboxylate 12, and/or 1,2,4-triazole 15 to give the corresponding biscompounds 4, 5, 7, 8, 10, 11, 13, 14, and 16, respectively. The structure of the synthesized compounds was elucidated by elemental analyses and spectral data. Some of the prepared compounds were tested for their antimicrobial and antitumor activities.