Pd(II) salen complex covalently anchored to multi‐walled carbon nanotubes as a heterogeneous and reusable precatalyst for Mizoroki–Heck and Hiyama cross‐coupling reactions

A Pd(II) salen complex anchored to multi‐walled carbon nanotubes showed excellent catalytic activity and stability for the Mizoroki–Heck and Hiyama cross‐couplings of aryl halides with olefins and phenylsiloxanes. Furthermore, the heterogeneous catalyst could be reused up to four times with the catalytic activity being recovered easily after simple manipulations. Copyright © 2014 John Wiley & Sons, Ltd.     

Facile construction of symmetric biaryls using (BeDABCO)2Pd2Cl6 as an efficient and highly active catalyst under microwave irradiation

An efficient catalytic system using (BeDABCO)₂Pd₂Cl₆ (BeDABCO, benzyl‐1,4‐diazabicyclo[2.2.2]octane) was developed for the homo‐coupling reaction of various aryl halides. Due to the combination of ionic homogeneous metal catalyst and microwave irradiation, symmetric biaryls were produced in excellent yields and short reaction times in N‐methyl‐2‐pyrrolidone at 120 °C. BeDABCO as an efficient ligand and also a quaternary ammonium salt had an efficient stabilizing effect on the Pd(0) species in this coupling reaction. Copyright © 2015 John Wiley & Sons, Ltd.     

Methionine: a green and efficient promoter for copper‐catalyzed Sonogashira cross‐coupling reactions

In the presence of amino acids as environmentally friendly ligands, CuI‐catalyzed Sonogashira cross‐coupling of various aryl halides with phenylacetylene was conducted to afford the corresponding internal alkynes. l ‐Methionine was found to be useful for this palladium‐free and amine‐free coupling reaction. It was also found that the solvent system plays an important role in this reaction, and significantly affects the product formation and reaction rate. Sonogashira coupling of aryl iodides and aryl bromides in dimethylsulfoxide or dimethylformamide gave the coupled products in good to excellent yields. Copyright © 2015 John Wiley & Sons, Ltd.     

New applications of cellulose-SO3H as a bio-supported and biodegradable catalyst for the one-pot synthesis of some three-component reactions

A bio-supported solid acid catalyst, cellulose-SO₃H, was used for three-component reactions to synthesize 2-amino-4-aryl-5-oxo-4H,5H-pyrano[3,2-c]chromene-3-carbonitriles, spirooxindoles, 2,3-dihydroquinazolin-4(1H)-ones, 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones, α-amidoalkyl-β-naphthols, and α-carbamato-alkyl-β-naphthols derivatives under solvent-free conditions.     

Density and viscosity of pyridinium-based ionic liquids and their binary mixtures with water at several temperatures

Densities and viscosities of two pyridinium-based ionic liquids, 1-butylpyridinium tetrafluoroborate [BuPy][BF₄] and 1-octylpyridinium tetrafluoroborate [OcPy][BF₄], and their binaries with water at atmospheric pressure and temperatures from (283.15 to 348.15) K were determined. The densities and viscosities of pure ionic liquids were correlated successfully by empirical equations. The Vogel–Fulcher–Tammann equations can fit the experimental viscosities for pure and binary of both IL systems. Excess molar volume and viscosity deviation were calculated for the binaries. The excess molar volumes have positive deviation from ideal solution while the viscosity deviations have negative values.     

Sol–gel combustion synthesis and characterization of nanostructure copper chromite spinel

Nanocomposite copper chromite spinel was fabricated by sol–gel process using copper nitrate trihydrate, chromium nitrate nonahydrate, ethylene glycol, diethyl ether, and citric acid. The thermoanalytical measurements (TG–DTG), X-ray powder diffractometry (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis were used to characterize the structural and the chemical features of the nanocomposites. TG–DTG results showed that the major mass loss for copper(II) nitrate, chromium(III) nitrate as precursors occur at 258 and 140 °C, respectively. The major mass loss for dried gel of copper chromite occurs at 310 °C. XRD data revealed the formation of pure copper chromite after thermal decomposition at 1,000 °C for 2 h. The observation of XRD patterns reveals the presence of single-phase tetragonal spinel CuCr₂O₄. FESEM analysis of calcined composite was found to be in the range of 20–30 nm.     

Dispersive solid phase extraction combined with dispersive liquid–liquid extraction for the determination of BTEX in soil samples: ant colony optimization–artificial neural network

In this study, dispersive solid phase extraction combined with dispersive liquid–liquid extraction has been developed for the extraction of benzene, toluene, ethylbenzene, and xylenes isomers (BTEX) in soil samples prior to gas chromatography–mass spectrometry. The BTEX were extracted from soil sample into acetonitrile by dispersive solid phase extraction method, and the extract was then used as dispersive solvent in dispersive liquid–liquid extraction procedure. Ant colony optimization–artificial neural network (ACO–ANN) has been employed to develop the model for simulation and optimization of this method. The volume of dispersive solvent, volume of extraction solvent, extraction time, and ultrasonic time were the input variables, while the multiple response function (R_m) of analytes was the output. The optimum operating condition was then determined by ant colony optimization method. At the optimum conditions, the limit of detections of 0.12–0.75 ng g⁻¹ was obtained for the BTEX. The developed procedure was then applied to the extraction and determination of BTEX in the soil samples and one certified soil. Copyright © 2015 John Wiley & Sons, Ltd.     

Design of a New Carbon Paste Electrode Modified with TiO2 Nanoparticles to Use in an Electrochemical Study of Codeine and Simultaneous Determination of Codeine and Acetaminophen in Human Plasma Serum Samples

A new electrochemical sensor was fabricated via TiO₂ nanoparticles onto a carbon paste electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studied the response of the modified electrode toward codeine. The effects of pH, modifier amount, pulse amplitude, and scan rate of potential have been examined. Using DPV, we could measure simultaneously codeine and acetaminophen in one mixture. The detection limits of 0.018 and 0.050 µmol L^?1 were achieved for codeine and acetaminophen, respectively. The electrooxidation pathway, transfer coefficient, and standard rate constant, are estimated. The proposed voltammetric sensor was successfully applied to determination of codeine and acetaminophen in human plasma serum samples.     

Expeditious Synthesis of Aromatic Cyanodienones Using Neutral Alumina as a Versatile Heterogeneous Catalyst

The work described herein employs neutral alumina as an effective catalyst for ring opening of triarylpyrylium perchlorates to corresponding aromatic cyanodienones, which have main roles in biological activities. The present porous catalyst has several advantages, it is inexpensive, thermally and mechanically stable, nontoxic, and highly resistant against organic solvents. It increases the reaction rate many fold when compared with conventional reaction conditions. Moreover, the recovered alumina can be used several times without serious decrease in activity.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]