Pyridine-catalyzed addition of diaryl-1,2-diones to dimethyl butynedioate leading to the formation of 1,2-diaroyl dimethyl maleates via an unprecedented rearrangement

[reaction: see text] Pyridine catalyzes the reaction of 1,2-diaryl diones with dimethyl butynedioate to afford diaroyl maleates. This unprecedented rearrangement involves a unique benzoyl migration and proceeds with complete stereoselectivity.     

Mesoporous iron phosphate as an active, selective and recyclable catalyst for the synthesis of nopol by Prins condensation

Mesoporous iron phosphate is found to be a highly active and recyclable heterogeneous catalyst for the selective synthesis of nopol by Prins condensation of beta-pinene and paraformaldehyde in acetonitrile at 80 degrees C.     

A parallel synthesis demonstration library of tri-substituted indazoles containing new antimutagenic/antioxidant hits related to benzydamine

A solution phase strategy for the multiple parallel synthesis of a demonstration library of indazoles is described by which regio-selectivity problems inherent to previous syntheses of this nucleus are largely overcome. Synthesis of selected components proceeded satisfactorily indicating that a fully realized library of indazole analogs could readily be produced using this methodology. Simple modifications of the basic nucleophilic aromatic substitution route unambiguously produce a range of N-1 substitutions (alkyl, aryl and aralkyl) in 50-75% yields. Next a range of substituents was introduced at the C-3 position in 50-80% yields by O-alkylation. Careful choice of reagents and reaction conditions were required to prevent by-product formation due to competing alkylation at N-2 (trace to 15% yields). When present, these contaminants were readily removed by chromofiltration. A third diversity site was sketched in at C-5 in 75-90% yield by reductive alkylation or acylation. Screening of some of the demonstration library members in vitro revealed highly active antioxidants suggesting that producing a full library would be worthwhile.     

On the role of solvent in complexation equilibria. I. The acid-base chemistry of some α,ω-diaminocarboxylic acids in water-dioxane mixed solvents

The macroscopic and microscopic acid-base chemistry of a series of α,ω-diaminocarboxylic acids, H₂N(CH₂)_nCH(NH₂)COOH [n=4, lysine (LYS);n=3, ornithine (ORN);n=2, 2,4-diaminobutyric acid (DAB);n=1, 2,3-diaminopropionic acid (DAP)], was determined in water and its binary mixtures with dioxane (20.5, 40.7, 60.7, and 80.5 mass % dioxane) using carbon-13 nuclear magnetic resonance spectroscopy. The macroscopic acid dissociation constants for the titration of the two ammonium groups decrease uniformly with increasing dioxane composition. The microscopic constants, however, which characterize the relative concentrations of the two tautomers of singly protonated amino acid (I and II) $$\begin{gathered} H_3 \mathop N\limits^ + (CH_2 )_n CHCOO^ - H_2 N(CH_2 )_n CHCOO^ - \hfill \\ || \hfill \\ NH_2 \mathop N\limits_ + H_3 \hfill \\ III \hfill \\ \end{gathered}$$ reveal that while tautomer I is favored in aqueous solution, tautomer II becomes more important with increasing dioxane composition for LYS and ORN. The relative concentrations of I and II remain unchanged with solvent composition for DAP. These results are explained in terms solute-solvent and solvent-solvent interactions.     

Spectrophotometric Determination of Hydrogen Peroxide Using Leucocrystal Violet in Micellar Medium

A simple and sensitive spectrophotometric method for the determination of hydrogen peroxide, based on the increase in color intensity of dye on addition of surfactant, is described. Hydrogen peroxide is first reacted with potassium iodide in acidic medium, in presence of ammonium molybdate to liberate iodine. The liberated iodine oxidizes leucocrystal violet to crystal violet having maximum absorbance at 593 nm. The color of the dye intensifies with the addition of the surfactant, cetyl pyridinium chloride though the absorption maximum remains the same. Beer's law is obeyed in the range 0.05–0.45 µg of hydrogen peroxide per 25 mL of final solution (0.002–0.018 µg mL^?1) with an excellent correlation coefficient (r = 0.9977). The proposed method has been successfully applied for the analysis of hydrogen peroxide in various food products and rainwater.     

A Novel Method for Permeability Estimation from Micro-tomographic Images

Transport in Porous Media - A methodology has been developed to create a pore network model (PNM) from the geometrical/topological information extracted from the micro-tomographic images of a...     

Quantum chemical DFT study of 4-azatricyclo [5.2.2.02,6] undecane-3,5,8-trione

Fourier-transform-Raman and infrared spectrum of 4-azatricyclo [5.2.2.0^2,6] undecane-3,5,8-trione were recorded and analyzed. The vibrational wavenumbers were examined theoretically using the Gaussian03 set of quantum chemistry codes, and the normal modes were assigned by potential energy distribution (PED) calculations. The first hyperpolarizability, predicted infrared intensities and Raman activities are reported. The calculated first hyperpolarizability is comparable with reported values of similar structures which makes this compound an attractive object for future studies of nonlinear optics. Optimized geometrical parameters of the compound are in agreement with similar reported structures. The red shift of the NH stretching wavenumber in the infrared spectrum from the computational wavenumber indicates the weakening of NH bond.     

Aligned magnetic effects through varying permeable bed

The aligned magnetic effects on a steady laminar, viscous, incompressible, conducting fluid down an open inclined channel bounded below by a bed of varying permeability has been studied when the free surface is exposed to atmospheric pressure. Beavers and Joseph slip condition at the interface of the free flow region and the fluid flow in the porous bed and the Darcy’s law in the porous medium have been used. The expressions for velocity, magnetic strength and the mass flow across the cross-section of the channel are obtained.     

Electrochemical Investigation of Activated Carbon Electrode Supercapacitors

Supercapacitors, also called as ultracapacitors, are electrochemical energy-storage devices that exploit the electrostatic interaction between high-surface-area nanoporous electrodes and electrolyte ions, combining properties of conventional batteries and conventional capacitors. A symmetrical activated carbon (AC) electrode supercapacitor has been fabricated in a simple and inexpensive manner. The AC has been synthesized from Charcoal, has activated in a furnace at high temperatures. The electrode was fabricated by casting slurry made of AC and blended in a polymer solution on the counter electrode (current collector), appeared to have high mechanical strength. The electrochemical performance of the prepared samples was tested in 1 M KCl solution by cyclic voltammetry (CV), galvanostatic charge discharge technique, and impedance spectroscopy. The surface and cross-section of electrode was observed with SEM. Capacitance of fabricated supercapacitor has a favorable capacitance in the range of 65–70 F/g with low resistance. The AC electrode supercapacitor has excellent electro chemical reversibility, good cycle stability with a low fading rate of specific capacitance even after 500 cycles, which is promising for energy storage applications.