Highly efficient epoxidation of alkenes with hydrogen peroxide catalyzed by tungsten hexacarbonyl supported on multi-wall carbon nanotubes

The preparation, characterization, and catalytic activity of W(CO)₆ supported on multi-wall carbon nanotubes modified with 4-aminopyridine is reported. The catalyst, [W(CO)₅@Apy-MWCNT], was characterized by physico-chemical and spectroscopic methods and found to be an efficient heterogeneous catalyst for green epoxidation of alkenes with hydrogen peroxide in MeCN solvent. The catalyst showed good stability and reusability properties in the epoxidation reactions.     

One‐pot synthesis of 2,3‐disubstituted‐2,3‐dihydroquinazolin‐4(1H)‐ones using [Hmim][NO3]: An eco‐friendly protocol

An efficient method for the synthesis of a series of 2,3‐disubstituted‐2,3‐dihydroquinazolin‐4(1H)‐ones is described via one‐pot condensation reaction of isatoic anhydride, aryl aldehydes, and primary amines using a Brønsted acidic ionic liquid, [Hmim][NO₃], as a catalyst and medium. The present protocol enjoys convenient reaction and simple work‐up, greenness, short reaction times, and reusable catalyst as well as mild reaction conditions. J. Heterocyclic Chem., (2011).     

Preparation, characterization and photocatalytic properties of InVO4 nanopowder and InVO4–TiO2 nanocomposite toward degradation of azo dyes and formaldehyde under visible light and ultrasonic irradiation

In this study, photocatalytic activity of InVO₄ and InVO₄–TiO₂ nanoparticles in the degradation of aqueous solutions of industrial textile azo dyes such as Solophenyl Red 3BL, Coperoxon Nevy Blue RL and Black Nilusun 2BC (abbreviated as SR 3BL, CNB RL and BN 2BC, respectively) and also formaldehyde (abbreviated as FAD) under visible light and ultrasonic irradiations has been compared. The effect of various parameters such as pH, temperature, irradiation time, amounts of nanophotocatalyst and nanocomposite, and ultrasonic intensity on degradation rates was investigated. Then based on the Langmuir–Hinshelwood approach, reaction rates and adsorption equilibrium constants were calculated. The nanophotocatalyst and nanocomposite were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and UV‐Vis spectroscopic methods. It was observed that InVO₄–TiO₂ nanopowder was more reactive than pure InVO₄ in the degradation of azo dyes under both conditions of visible light and ultrasonic irradiations. It was noticeable that degradation percent was more under ultrasonic irradiation rather than under visible light irradiation.     

MoO<Subscript>2</Subscript>(acac)<Subscript>2</Subscript> supported on MCM-41: An efficient and reusable catalyst for alkene epoxidation with <Emphasis Type="Italic">tert</Emphasis>-BuOOH

A new heterogeneous catalyst prepared by immobilization of MO₂(acac)₂ on Mobil Catalytic Material, MCM-41, is reported. This catalyst, MoO₂(acac)₂-MCM-41, was successfully applied for efficient epoxidation of olefins with tert-BuOOH in 1,2-dichloroethane as solvent. The catalyst was characterized by elemental analysis, FT-IR, UV-Vis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). This catalyst can be reused several times without significant loss of its catalytic activity.     

Biomimetic epoxidation of alkenes with sodium periodate catalyzed by tetraphenylporphyrinatomanganese(III) chloride supported on multiwall carbon nanotubes

The biomimetic epoxidation of alkenes catalyzed by tetraphenylporphyrinatomanganese(III) chloride, [Mn(TPP)Cl], immobilized on multiwall carbon nanotubes modified with 4-aminopyridine and 4-aminophenol is reported. These heterogenized catalysts were used as efficient and reusable catalysts for epoxidation of a variety of cyclic and linear alkenes with sodium periodate under mild conditions. The catalysts, [Mn(TPP)Cl@amine-MWCNT], were characterized by physico-chemical and spectroscopic methods. The effect of ultrasonic irradiation on these catalytic systems was also investigated. The catalysts were reused several times without loss of their activity.     

Determination of mono- and dichloroacetic acids in betaine media by liquid chromatography

A simple and sensitive method has been developed for the analysis of residue amounts of chloroacetic acids in betaine samples based on derivatization by 1-naphthylamine (NA). The derivatized compounds are analyzed by reverse phase high performance liquid chromatography using methanol and water as mobile phase in the ratio of 32/68 (v/v) and phenyl column and PDA detection at 222 nm. The detection limits (LOD) of monochloroacetic acid (MCA) and dichloroacetic acid (DCA) are 0.1 and 0.15 μg mL⁻¹, respectively. The limits of quantification (LOQ) and the linear dynamic ranges (LDR) of MCA are found to be 1 and 1-400 μg mL⁻¹, respectively, and for DCA are found to be 3 and 3-400 μg mL⁻¹, respectively. The precision at the 5 ppm level for MCA and DCA are about 3% and 2%, (n = 5), respectively. The average recovery for MCA and DCA spiked to betaine samples are 98% and 97%, respectively.