Electrochemical determinations of 6-mercaptopurine on the surface of a carbon nanotube-paste electrode modified with a cobalt salophen complex

A mixture of multi-walled carbon nanotube/graphite paste electrode modified with a salophen complex of cobalt was prepared and was applied for the study of the electrochemical behavior of 6-mercaptopurine (MP) using cyclic and differential pulse voltammetry (DPV). An excellent electrocatalytic activity toward the oxidation of MP was achieved, which led to a considerable lowering in the anodic overpotential and remarkable increase in the response sensitivity in comparison with unmodified electrode. Utilizing DPV method, a linear dynamic range of 1–100 μM with detection limit of 0.1 μM was obtained in phosphate buffer of pH 3.0. The electrochemical detection system was very stable, and the reproducibility of the electrode response, based on the six measurements during 1 month, was less than 3.0% for the slope of the calibration curves of MP. The electrochemical method as a simple, sensitive, and selective method was developed for the determination of MP in pharmaceutical dosage form and human plasma without any treatments.     

SELECTIVE OXIDATION OF BENZYLIC ALCOHOLS USING CAN SUPPORTED ONTO SILICA GEL UNDER MICROWAVE IRRADIATION

Cerium ammonium nitrate (CAN) adsorbed on HNO ₃ /silica gel is a mild reagent for selective oxidation of benzylic alcohols to the corresponding aldehydes under microwave irradiation in solventless system.     

Efficient Synthesis of Bis-Coumarins Using Silica-Supported Preyssler Nanoparticles

Reaction of aldehydes and 4-hydroxycoumarin in the presence of catalytic amount of silica-supported Preyssler nanoparticles led to synthesis of bis-coumarins in excellent yields.     

Efficient,Rapid, and Regioselective Bromination of Phenols and Anilines with N-Bromosaccharin Using Tungstophosphoric Acid as a Heterogeneous Recyclable Catalyst

A simple, efficient, and rapid method for high-yielding regioselective mono bromination of phenols and anilines has been achieved by treatment with N-bromasaccharin in the presence of a catalytic amount of tungstophosphoric acid.     

Palladium-Catalyzed Synthesis of Symmetrical Biaryls Under Microwave Irradiation and Conventional Heating

The activity of the [Pd{C₆H₄(CH₂N(CH₂Ph)₂)}(µ-Br)]₂ complex was investigated in the synthesis of symmetrical biaryls under both conventional and microwave irradiation conditions, and their results were compared. This complex is efficient, stable, and not sensitive to air or moisture and is a catalyst for the homo-coupling reaction of aryl iodides, bromides, and even chlorides. The products were produced in excellent yields in short reaction times using a catalytic amount of [Pd{C₆H₄(CH₂N(CH₂Ph)₂)(µ-Br)]₂ complex in N-methylpyrolidine (NMP) at 130 °C. In comparison to conventional heating conditions, the reactions under microwave irradiation gave better yields in shorter reaction times.     

Brønsted Acidic Ionic Liquids: New,Efficient, and Green Promoter System for the Synthesis of 4(3H)-Quinazolinones

A simple, inexpensive, and efficient new synthesis of 4(3H)-quinazolinones from the reaction of 2-aminobenzamide with aroyl chlorides in the presence of two new halogen-free Brønsted acidic ionic liquids, 3-methyl-1-(4-sulfonic acid)butylimidazolium hydrogen sulfate [(CH₂)₄SO₃HMIM][HSO₄] and 1-(4-sulfonic acid) butylpyridinium hydrogen sulfate [(CH₂)₄SO₃HPY][HSO₄], green and reusable catalysts, with excellent product yields under solvent-free conditions is reported. The products could be separated simply from the catalyst, and the catalyst could be recycled without noticeably decreasing the catalytic activity.     

NH2SO3H and H6P2W18O62 · 18H2O-Catalyzed,Three-Component,One-Pot Synthesis of Benzo[c]acridine Derivatives

We report here two simple methods for the synthesis of benzo[c]acridine derivatives from three-component, one-pot condensation of 1-naphthylamine, dimedone, and a variety of substituted aldehydes in the presence of a catalytic amount of NH₂SO₃H or H₆P₂W₁₈O₆₂ · 18H₂O under solvent-free conditions at 120 °C or in refluxing ethanol.     

‘Click Synthesis’ of Some Novel O‐Substituted Oximes Containing 1,2,3‐Triazole‐1,4‐diyl Residues as New Analogs of β‐Adrenoceptor Antagonists

The ‘click synthesis’ of some novel O‐substituted oximes, 7a – 7t , which contain 1,2,3‐triazolediyl residues, as new analogs of β‐adrenoceptor antagonists is described (Schemes 1–4). The synthesis of these compounds was achieved in four to five steps. The formation of oximes of 9H‐fluoren‐9‐one and benzophenone, i.e., 9a and 9b , respectively, followed by their reaction with propargyl bromide, afforded O‐propargyl oximes 10a and 10b , respectively, which by a subsequent CuI‐catalyzed Huisgen cycloaddition with prepared β‐azido alcohols 11a – 11j (Schemes 2 and 3), led to the target compounds 7a – 7t in good yields.     

Uranium recovery from UCF liquid waste by nanoporous MCM-41: breakthrough capacity and elution behavior studies

Adsorption and recovery of uranium by nanoporous MCM-41 from aqueous solutions (synthetic solution and uranium conversion facility liquid waste) were investigated by use of a fixed-bed column (1.2 cm diameter and 3.0 cm height). Adsorption was carried out at flow rates 0.2 and 0.5 mL min^?1, which correspond to retention times of 10 and 6 min. The maximum breakthrough capacity for uranium ions was achieved by use of nanoporous MCM-41 at the optimum pH of 3.6 and flow rate 0.2 mL min^?1 (61.95 μg g^?1). The Thomas and Yan models were applied to the experimental data, by use of linear regression, to determine the characteristics of the column for process design. The breakthrough curves calculated from the models were in good agreement with the experimental data. The elution behavior of uranium on nanoporous MCM-41 was studied with different eluents; the results showed that 0.1 M HCl is good eluent for uranium recovery. The regenerated column could be used in a multitude of adsorption–desorption cycles.