Synthesis of New 1,4-Dihydropyridine Derivatives Containing Thiazolyl Substituents

A series of 4-[2-methyl (or aryl) thiazole-4-yl]-2,6-dimethyl-3,5-diacetyl (or dibenzoyl) 1,4-dihydropyridines were synthesized using a modified Hantzsch reaction involving the condensation of the corresponding aldehyde with acetyl acetone or benzoyl acetone. The preparation of the corresponding aldehydes (2-methylthiazole-4-carboxaldehyde and some 2-arylthiazole-4-carboxaldehydes) was achieved by a simplified protocol of the published synthesis.     

POLY [N-(4-PYRIDINIUM DICHROMATE)-P-STYRENE SULPHONAMIDE] AS AN EFFICIENT REAGENT FOR OXIDATION OF ALCOHOLS

POLY [N-(4-PYRIDINIUM DICHROMATE)-P-STYRENE SULPHONAMIDE] is readily prepared. It is a stable, mild, and efficient oxidizing reagent that can be used for oxidation of different alcohols to their corresponding carbonyl compounds in approtic solvents. This polymer can be synthesized from the reaction between poly [N-(4-pyridyl)-p-styrene sulphonamide] and CrO ₃ in a minimum amount of water. The latter polymer was prepared by free radical polymerization of [N-(4-pyridyl)-p-styrene sulphonamide] by using azobis(isobutyronitrile) (AIBN) as an initiator. N-(4-pyridyl)-p-styrene sulphonamide was synthesized from commercial 4-vinyl benzene sulphonic acid sodium salt and 4-amino pyridine. POLY [N-(4-PYRIDINIUM DICHROMATE)-P-STYRENE SULPHONAMIDE] can oxidize both aliphatic and aromatic alcohols in good yields at a temperature of 38°C and in CH ₂ Cl ₂ as solvent. One advantage in using this reagent is the mild condition of the reaction system. The synthesized compounds including polymeric reagent and carbonyl compounds were identified by HNMR and IR spectroscopy.     

Preparation and application of carbon nanotubes/poly(o‐toluidine) composite fibers for the headspace solid‐phase microextraction of benzene,toluene, ethylbenzene,and xylenes

A novel nanocomposite coating of poly(o‐toluidine) and oxidized multiwalled CNTs (MWCNTs, where CNTs is carbon nanotubes) was electrochemically prepared on a stainless‐steel wire. The applicability of the fiber was assessed for the headspace solid‐phase microextraction of benzene, toluene, ethylbenzene, and xylenes in aqueous samples followed by GC with flame ionization detection. In order to obtain an adherent and stable composite coating, several experimental parameters related to the coating process, such as polymerization potential and time, and the concentration of o‐toluidine and oxidized MWCNTs were optimized. The combination of MWCNTs and polymer in a nanocomposite form presents desirable opportunities to produce materials for new applications. The effects of various parameters on the efficiency of the headspace solid‐phase microextraction process, such as desorption temperature and time, extraction temperature and time, and ionic strength were also investigated. At the optimum conditions, LODs were 0.03–0.06 μg/L. The method showed linearity in the range of 0.5–300 μg/L with coefficients of determination >0.99. The intraday and interday RSDs obtained at a 5 μg/L concentration level (n = 5) using a single fiber were 1.2–5.2 and 3.2–7.5%, respectively. The fiber‐to‐fiber RSD (%; n = 3) at 5 μg/L was 6.1–9.2%.     

Zinc–aluminum layered double hydroxide as a nano-sorbent for removal of Reactive Yellow 84 dye from textile wastewater effluents

In this research, the zinc–aluminum layered double hydroxide (Zn–Al LDH) was synthesized and structurally and morphologically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and N₂ adsorption–desorption techniques. The obtained nano-structured inorganic material was employed as an innovative nano-sorbent for separation of Reactive Yellow 84 (RY84) dye from aqueous solutions, which can be spectrophotometrically monitored at λ = 359 nm. The effect of several parameters such as type of interlayer anion in Zn–Al LDH structure, pH, sample flow rate, elution conditions, amount of nano-sorbent, sample volume and co-existing ions on the retention efficiency was investigated and optimized. The results showed that trace amounts of the RY84 could be retained using a column packed with 300 mg of the Zn–Al(NO₃ ^?) LDH at pH 8 and stripped by 2.5 mL of 3.0 mol L^?1 NaOH. Under the optimum experimental conditions, the limit of detection and the relative standard deviation were 0.04 μg mL^?1 and 1.8 %, respectively. The calibration graph using the presented solid phase extraction system was linear in the range of 0.15–1.5 μg mL^?1 with a correlation coefficient of 0.9982. The method was successfully applied to removal of RY84 from several textile wastewater effluents.     

A Quick and Clean Procedure for Synthesis of α‐Aminophosphonates in Aqueous Media

A green and efficient procedure for the synthesis of α‐aminophosphonates has been developed in water as a green and nonhazardous solvent, from condensation between aromatic aldehydes, aniline, and triphenyl phosphite at 80°C. This methodology has a number of advantages including clean reaction conditions, easy work‐up, and environmentally friendly.     

Effective removal of uranium ions from drinking water using CuO/X zeolite based nanocomposites: effects of nano concentration and cation exchange

For the first time, effects of CuO nanoparticles concentration (from 1 to 24.2 wt%) in CuO/NaX nanocomposite and replacing various cations (Ag⁺, K⁺, Ca²⁺, and Mg²⁺) with Na⁺ ions in NaX zeolite on removal of uranium ions from drinking water are reported. The removal of uranium was performed under natural conditions of pH, laboratory temperature and the presence of competing cations and anions that are available in tap water of Isfahan city. Characterization of parent NaX zeolite and modified samples were investigated using X-ray fluorescence, X-ray powder diffraction patterns, scanning electron microscopy, and atomic absorption spectroscopy methods. Using Langmuir, Freundlich, and C-models, isotherms of equilibrium adsorption were studied. Results show the removal efficiency and distribution coefficient of NaX zeolite decrease in the presence of other competing anions and cations that exist in drinking water. But, modification of NaX zeolite with various cations and CuO nanoparticles might enhance the ability of X zeolite in removing uranium from drinking water.     

以淀粉溶液为催化剂锅三组分法合成四氢苯并[b]吡喃和3,4-二氢吡喃并[c]苯并吡喃衍生物简

Tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives were synthesized via a one-pot three-component condensation of aromatic aldehydes with malononitrile and dimedone or 4-hydroxycoumarin in excellent yields in the presence of starch solution as a highly efficient homogenous catalyst. The use of a nontoxic and biodegradable catalyst, simple work-up procedure, and short reaction time are advantages of this method.     

Influence of copper cations on the magnetic properties of NiCuZn ferrite nanoparticles

Ni_0.6−xCu_xZn_0.4Fe₂O₄ (x=0-0.5) ferrite nanoparticles were prepared, employing a reverse micelle process. X-ray diffraction and transmission electron microscopy evaluations demonstrated that single phase spinel ferrites with narrow size distribution were obtained. Vibrating sample magnetometer was employed to probe the magnetic properties of the samples. It was found that with an increase in copper content, the saturation magnetization decreases. Magnetic dynamics of the samples was studied by measuring a.c. magnetic susceptibility versus temperature at different frequencies. The phenomenological Néel-Brown and Vogel-Fulcher models were employed to distinguish between the interacting or non-interacting systems. The system exhibits that there is strong interaction among fine particles.     

Ab-Initio Molecular Dynamics Simulation of Condensed-Phase Reactivity: The Electrolysis of Amino Acids and Peptides

Electrolysis is a potential candidate for a quick method of wastewater cleansing. However, it is necessary to know what compounds might be formed from bioorganic matter. We want to know if there are toxic intermediates and if it is possible to influence the product formation by the variation in initial conditions. In the present study, we use Car–Parrinello molecular dynamics to simulate the fastest reaction steps under such circumstances. We investigate the behavior of amino acids and peptides under anodic conditions. Such highly reactive situations lead to chemical reactions within picoseconds, and we can model the reaction mechanisms in full detail. The role of the electric current is to discharge charged species and, hence, to produce radicals from ions. This leads to ultra-fast radical reactions in a bulk environment, which can also be seen as redox reactions as the oxidation states change. In the case of amino acids, the educts can be zwitterionic, so we also observe complex acid–base chemistry. Hence, we obtain the full spectrum of condensed-phase chemistry.     

Computational analysis of heat transfer in a PEM fuel cell with metal foam as a flow field

Journal of Thermal Analysis and Calorimetry - Thermal management of proton-exchange membrane (PEM) fuel cell has an important effect on the overall cell performance. In this paper, metal foams as...