A simple and efficient procedure for the synthesis of benzimidazoles using trichloroisocyanuric acid (TCCA) as the oxidant

A Direct one step synthesis of various benzimidazoles from 3,4‐diaminotoluene and benzaldehydes is described using TCCA as the oxidant. The salient features of this method include simple procedure, mild condition, no waste products, easy separation, low reaction times and generality.     

Fischer–Tropsch reaction over a Co<Subscript>2</Subscript>-Ni-Mn/SiO<Subscript>2</Subscript> nanocatalyst prepared by thermal decomposition of a new precursor

This study was prepared for the first time the trimetallic nanocatalyst Co₂-Ni-Mn/SiO₂ by thermal decomposition of) [Ni(H₂O)₅Co(dipic)₂].2H₂O + [Mn(H₂O)₅Co(dipic)₂] 2H₂O)/SiO₂, to study the Fischer–Tropsch reaction for conversion of the synthesis gas to light olefins. The catalytic performance of Co₂-Ni-Mn/SiO₂ as a nanocatalyst prepared by thermal decomposition of an inorganic precursor was compared to that of the trimetallic nanocatalysts Co₂-Ni-Mn/SiO₂ as reference nanocatalysts prepared by impregnation and co-precipitation. The characterization of precursor and nanocatalyst were confirmed by thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) specific surface area, and X-ray diffraction (XRD). The Fischer–Tropsch reaction for all nanocatalysts of Co₂-Ni-Mn/SiO₂ was studied at 280–360 °C at a gas hourly space velocity of 3600 h^?1, and a H₂/CO molar ratio of 1:1 at atmospheric pressure. The results showed that the Co₂-Ni-Mn/SiO₂ nanocatalyst prepared by thermal decomposition of an inorganic complex exhibited the higher activity than the other nanocatalysts and showed maximum selectivity to light olefins at 360 °C.     

Determining urea levels in dialysis human serum by means of headspace solid phase microextraction coupled with ion mobility spectrometry and on the basis of nanostructured polypyrrole film

A simple and sensitive headspace (HS) solid phase microextraction (SPME) coupled with ion mobility spectrometry (IMS) method is presented for analysis of urea in dialysis human serum samples. A dodecylbenzenesulfonate-doped polypyrrole coating was used as a fiber for SPME. The HS-SPME–IMS method exhibits good repeatability (relative standard deviation of 3 % or less), simplicity, and good sensitivity. The influence of various analytical parameters such as pH, ionic strength, extraction time and temperature was investigated and the parameters were optimized. The calibration graph was linear in the range from 5 to 50 μg mL^?1, and the detection limit was 2 μg mL^?1. The method was applied successfully for determination of urea in human serum and with acceptable recovery (more than 98 %). Finally, a standard addition calibration method was applied to the HS-SPME-IMS method for the analysis of human serum samples before and at the end of dialysis. The proposed method appears to be suitable for the analysis of urea in serum samples as it is not time-consuming and requires only small quantities of the sample without any derivatization process.

Fe3O4/Graphene Composite Anode Material for Fast-Charging Li-Ion Batteries

Composite anode material based on Fe₃O₄ and reduced graphene oxide is prepared by base-catalysed co-precipitation and sonochemical dispersion. Structural and morphological characterizations demonstrate an effective and homogeneous embedding of Fe₃O₄ nanoparticles in the carbonaceous matrix. Electrochemical characterization highlights specific capacities higher than 1000 mAh g⁻¹ at 1C, while a capacity of 980 mAhg⁻¹ is retained at 4C, with outstanding cycling stability. These results demonstrate a synergistic effect by nanosize morphology of Fe₃O₄ and inter-particle conductivity of graphene nanosheets, which also contribute to enhancing the mechanical and cycling stability of the electrode. The outstanding capacity delivered at high rates suggests a possible application of the anode material for high-power systems.     

Synthesis of 1,3,4-oxadiazoles from the reaction of N-isocyaniminotriphenylphosphorane (NICITPP) with cyclohexanone,a primary amine and an aromatic carboxylic acid via intramolecular aza-Wittig reaction of in situ generated iminophosphoranes

The 1:1 imine intermediate generated by the addition of a primary amine to cyclohexanone trapped by N-isocyaniminotriphenylphosphorane (NICITPP) in the presence of aromatic carboxylic acids and the corresponding iminophosphorane intermediate was formed. Disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were completed in neutral conditions at room temperature (18-26°C). The disubstituted 1,3,4-oxadiazole derivatives were produced in excellent yields.     

Analysis of Malathion pesticide residues in rice samples using ultrasound-assisted emulsification-microextraction coupled to UV photoionization source ion mobility spectrometry

The present paper describes the validation of ultrasound-assisted emulsification-microextraction method followed by ion mobility spectrometry (IMS) for determination malathion pesticides. Ultrasound radiation was applied for accelerating the emulsification of microliter organic solvent in aqueous solutions and enhancing the microextraction efficiency. This preconcentration step combined with IMS detection provided a precise and accurate method for determination of trace amounts of malathion pesticides. The effect of parameters influencing the extraction efficiency such as sonication time, type of extraction solvent, extraction solvent volume, and salt concentration were investigated and discussed. Under the optimum conditions, enrichment factors was 270 with corresponding LOD of 4 μg/L. Linearity with a coefficient of estimation (r²) were >0.99 in the concentration level range of 6–750 μg/L for extraction of Malathion in water samples. The applicability of the proposed method was evaluated by determination of the residues of the investigated pesticide in rice paddy water gathered from four stations during 60 days after spraying (June 2014), and in storage rice samples in Mazandaran province, Iran.     

SiO2 Nanoparticle‐catalyzed Facile and Efficient One‐pot Synthesis of N‐alkyl‐2,5‐bis[(E)‐2‐phenylvinyl]‐1,3‐dioxol‐4‐amine Under Solvent‐free Conditions

1,3‐Dioxole‐4‐amine derivatives have been prepared efficiently in one‐pot reaction using nanosized SiO₂ as a heterogeneous catalyst. The present method does not involve any hazardous organic solvents or catalysts. The high surface‐to‐volume ratio of SiO₂ nanoparticle has promising features for the reaction response such as the short reaction time, good to excellent yields, easy of operation and work‐up procedure, and purification of products by non‐chromatographic methods.     

以淀粉溶液为催化剂一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(英文)

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.