Light-induced dehydrogenation of 3,4-dihydropyrimidin-2(1H)-ones

Abstract  

UV light irradiation of Biginelli 3,4-dihydropyrimidin-2(1H)-ones in chloroform in an argon atmosphere leads to dehydrogenation of these compounds to their corresponding pyrimidin-2(1H)-ones in excellent yields. Irradiation in the same solvent under an oxygen atmosphere generates, in addition, various hitherto unidentified products. A light-induced electron transfer from the substrate to the solvent is proposed as the initial event, supported by the detection of dichloromethane and hydrogen chloride in the photolysate.     

Synthesis and characterization of nickel(II) complexes with three potentially hexadentate Schiff-base ligands and polyamines: X-ray crystal structure determination of one nickel(II) complex

Three new potentially hexadentate N₄O₂ Schiff-base ligands (H₂L¹, H₂L² and H₂L³) were prepared from the reaction of the polyamines N,N′-bis(2-aminophenyl)-1,2-ethanediamine (L¹), N,N′-bis(2-aminophenyl)-1,3-propanediamine (L²) and N,N′-bis(2-aminophenyl)-1,4-butanediamine (L³), respectively with salicylaldehyde. Reaction of the Schiff bases with Ni(II) salts in the presence of N(Et)₃ gave the neutral complexes [NiL⁴], [NiL⁵] and [NiL⁶]. Ni(II) complexes of the polyamines were also prepared. One of complexes [Ni(L¹)(MeCN)₂](ClO₄)₂·MeCN has been characterized through X-ray diffraction methods.     

Facile Catalyzed Preparation of 14‐Aryl‐ or Alkyl‐14‐H‐dibenzo[a,j]xanthenes by Dodecylphosphonic Acid and Dodecylsulfamic Acid: Environmentally Benign Methods

Under mild‐ and solvent‐free conditions, one‐pot preparation of 14‐alkyl‐ or 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes could proceed in the presence of catalytic amounts of dodecylphosphonic acid (DPA) and dodecylsulfamic acid (DSA) in good to excellent yields. In these reactions, DPA and DSA are recovered by straightforward work‐ups.     

The influence of hydrophobic amino acid side groups on the acidity of the aromatic imidazole ring of histidine: A theoretical study

In this study we have calculated the acidity constant (pKa) of imidazole ring in Histidine‐Hydrophobic amino acid dipeptides using the quantum chemistry and continuum solvation methods. Density functional theory calculations with the large basis sets are used to determine the Gibbs free energy of deprotonate in the gas and liquid phases. Based on our results ΔG_S values are located between ?69.38 and ?18.82 kcal mol^?1 which are related to His⁺–Gly and His forms, respectively. pKa of the dipeptides in the aqueous phase was obtained from the calculated gas‐phase and solvation free energies through a thermodynamic cycle and the solvation model chemistry of Martin Karplus et al. Solvation effects are treated using a self‐consistent reaction field formalism involving polarized continuum models. According to our calculations pKa values are between 5.50 and 8.19 that are belong to His⁺–ILe and His⁺–Ala forms, respectively. Natural bond orbital analysis of dipeptides reveals that the electron delocalization in imidazole ring is the most effective factor in determination of acidity order for these compounds. Structural analysis confirmed that the orientation of carbonyl group with respect to imidazole ring is an effective factor in imidazole ring stability. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

ZnO nanoparticles and poly(acrylic) acid-based polymer gel electrolyte for photo electrochemical cell

This work presents a photo electrochemical cell based on zinc oxide (ZnO) nanoparticles and poly(acrylic) acid (PAA) doped with sodium iodide (NaI) and iodine (I₂) polymer gel electrolyte. The ZnO powders were synthesized by sol–gel storage and sol–gel centrifugation. The ZnO powder synthesized via sol–gel centrifugation showed the optimal structural properties, with largest crystallite sizes of 58 nm, average particles size between 20 and 80 nm and indirect band gap energy of 3.20 eV. The highest conductivity [(8.0 ± 0.1) × 10^?2 S cm^?1] was obtained for PAA + 0.8 M NaI + 0.02 M I₂. This sample achieved the lowest activation energy (0.029 eV) and electrochemical stability at 1.6 V. The ZnO powder synthesized via sol–gel centrifugation and PAA + 0.8 M NaI + 0.02 M I₂ was fabricated as a Cu–ZnO/PAA + 0.8 M NaI + 0.02 M I₂/C-ITO photo electrochemical cell.     

Preparation, characterization, and theoretical studies of azelaic acid derived from oleic acid by use of a novel ozonolysis method

Environmentally friendly manufacture of organic compounds has been intensively reexamined in recent years. Many excellent methods have been devised to produce organic compounds from renewable resources. Azelaic acid has been produced by ozonolysis of oleic acid. The reaction was performed in a Bach bubbling reactor, with fine bubbles, at high temperature (150 °C) without utilizing any catalyst or any solvent. Yield of the reaction was 20% after 2 h. Production of azelaic acid was confirmed by use of FT-IR and ¹H NMR spectroscopic data and high-performance liquid chromatography of both synthesized and reference azelaic acid. A theoretical study was performed to obtain quantum chemical data for azelaic acid and to optimize the molecule’s geometry.     

费托合成反应中纳米铁催化剂上La和Ba助剂的协同效应(英文)

Effect of promoters such as Barium and Lanthanum has been investigated on the conventional nanostructured iron catalyst in Fischer-Tropsch synthesis (FTS). The nanosized iron-based catalysts were prepared by a microemulsion method with the general formulation of 100Fe/4Cu, 100Fe/4Cu/2La, 100Fe/4Cu/ 1La/1Ba, and 100Fe/4Cu/2Ba. The phase, structure, and morphology of the catalysts were characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy, temperature-programmed desorption of CO2, and temperature- programmed reduction. The results indicated that the addition of promoters could improve the activity of Fe catalysts for FTS and WGS (water-gas shift reaction) and lower the gas fraction at the outlet. In addition, both Ba- and La-promoted Fe catalysts exhibit the highest activity due to the synergetic effect.     

Dispersive liquid-liquid microextraction followed by spectrofluorimetry as a simple and accurate technique for determination of thiamine (vitamin B1)

Dispersive liquid-liquid microextraction (DLLME) combined with spectrofluorimetry was applied to the extraction, pre-concentration and analysis of thiamine (vitamin B₁). The procedure is based on (a) the oxidation of thiamine with ferricyanide to form fluorescent thiochrome (TC), (b) the trapping of TC into a microextraction solvent, and (c) spectrofluorometric determination. Microextraction solvent and disperser solvent are directly injected into an aqueous solution containing TC. After centrifuging, phase separation is performed by sedimenting the fine droplets of the microextraction solvent on the bottom of a test tube. The settled phase is transferred into a fluorometer for the determination of thiamine at excitation/emission wavelengths of 375/438 nm. Under the optimized experimental conditions, the method provides a linear dynamic range of 0.2–100 ng mL^?1, a detection limit of 0.06 ng mL^?1, and a relative standard deviation of 3.0%. The method was successfully applied to pharmaceutical formulations and human urine. The results were validated by recovery test and by comparison with other methods, and were found to be highly satisfactory.