Molybdenum (VI)‐functionalized UiO‐66 provides an efficient heterogeneous nanocatalyst in oxidation reactions

A novel heterogeneous nanocatalyst was established by supporting molybdenum (VI) on Zr₆ nodes in the structure of the well‐known UiO‐66 metal–organic framework (MOF). The structure of the UiO‐66 before and after Mo (VI) immobilization was confirmed with XRD, DR‐FTIR and UV–vis spectroscopy, and the presence and amount of Mo (VI) was identified by X‐ray photoelectron spectroscopy and inductively coupled plasma atomic emission spectroscopy. TEM imaging confirmed the absence of Mo clusters on the MOF surface, while SEM confirmed that the appearance of the MOF has not changed upon immobilizing the Mo (VI) catalyst. BET adsorption measurements were used to confirm the porosity of the catalyst. The catalytic activity of this heterogeneous catalyst was investigated in oxidation of sulfides with H₂O₂ in acetonitrile and oxidative desulfurization of dibenzothiophene. Easy work up, convenient and steady reuse and high activity and selectivity are prominent properties of this new hybrid material.     

New Re(I) tricarbonyl-diimine complexes with N,N′-bis(substituted benzaldehyde)-1,2-diiminoethane Schiff base ligands: Synthesis,spectroscopic and electrochemical studies and crystal structures

The syntheses, structures and spectroscopic properties of tricarbonylrhenium(I) complexes with N,N′-bis(2-bromo, 4-bromo, 4-chloro and 3-methoxybenzaldehyde)-1,2-diiminoethane Schiff base ligands have been investigated in this paper. Characterization of these complexes was carried out with FTIR, NMR, UV–Vis spectroscopy, elemental analysis and X-ray crystallography. The electrochemical behavior of the investigated complexes has been studied by cyclic voltammetry. The crystal structures of the 4-chloro, 4-bromo and 4-methoxy substituted complexes are stabilized by intermolecular C–H?Cl and C–H?O hydrogen bonds. The remarkable features of the 2-bromo, 4-bromo and 4-chloro substituted complexes are short intermolecular halogen–oxygen contacts. In the 4-bromo complex, short intermolecular Br?O and O?O contacts link neighboring molecules along the [1 0 0] direction, which are further stabilized by short intermolecular π?π interactions. In 2-bromo complex, intermolecular Br?O interactions link neighboring molecules into 1D extended chains along the [0 1 0] and [0 0 1] directions, forming a 2D network which is parallel to the bc-plane.     

Microwave-promoted efficient conversion of acetophenones to 1,3,5-triarylbenzenes catalyzed by H3PW12O40 and nano-silica supported H3PW12O40 as reusable catalysts

H₃PW₁₂O₄₀ and nano-silica supported H₃PW₁₂O₄₀ were found to be efficient heterogeneous catalysts for the preparation of 1,3,5-triarylbenzenes via triple self condensation of acetophenones under microwave irradiation and solvent-free conditions. High yields, short reaction times, easy work-up, easy availability and handling, eco-friendly and reusability of the catalysts are the main aspects of the present method. The catalytic mechanism of 1,3,5-triarylbenzenes synthesis is also proposed.     

Rapid and Efficient Synthesis of Imidazolines and Bisimidazolines Under Microwave and Ultrasonic Irradiation

Small assemblies of 2-imidazolines and bisimidazolines from appropriate nitriles and ethylenediamine with catalytic amounts of P₂S₅ employing a microwave assisted protocol were prepared. Sonication of this system also led to successful synthesis of 2-imidazolines and bisimidazolines. Another advantage of these systems is the ability to carry out large scale reactions.     

Efficient synthesis of symmetrical and unsymmetrical acyclic imides catalyzed by reusable 12-tungstophosphoric acid under thermal conditions and microwave irradiation

An efficient and environmentally friendly procedure has been developed for the synthesis of symmetrical and unsymmetrical acyclic imides by the reaction of nitriles with acyclic anhydrides in the presence of catalytic amounts of 12-tungstophosphoric acid (H₃PW₁₂O₄₀) under thermal conditions and microwave irradiation. It was found that microwave improves the yields and significantly reduces the reaction times. Furthermore, the catalyst could be recovered and reused several times without decrease in its activity.     

Highly efficient epoxidation of alkenes with sodium periodate catalyzed by reusable polystyrene-bound ruthenium(III) salophen

In this paper, highly efficient epoxidation of alkenes catalyzed by ruthenium(III) salophen chloride, [Ru(salophen)Cl], supported on functionalized chloromethylated polystyrene, PS, is reported. The PS was modified with 1,4-diaminobenzene, 4-aminophenol and 4-aminothiophenol, and [Ru(salophen)Cl] was attached to the supports via axial ligation. The prepared catalysts were used for efficient epoxidation of alkenes with NaIO₄ at room temperature. These new heterogenized catalysts were characterized by elemental analysis, FT-IR spectroscopy, scanning electron microscopy and transmission electron microscopy. The heterogeneous catalysts were reusable in the oxidation reactions and were reused several times.     

Facile and green synthesis of triarylmethanes using silica sulfuric acid as a reusable catalyst under solvent-free conditions

A facile and environmentally-benign protocol has been developed for the synthesis of triarylmethanes (TAMs) from the reaction of different arenes and aldehydes in the presence of silica sulfuric acid (SSA) as a heterogeneous and reusable catalyst under solvent-free conditions. Easy work-up, short reaction times, high yields, high selectivity, mild and green conditions are other salient features of this method.     

[C6(MIm)2]2W10O32. 2H2O: A novel and powerful catalyst for the synthesis of 4-arylidene-2-phenyl-5(4)-oxazolones under ultrasonic condition

Di[1,6-bis(3-methylimidazolium-1-yl)hexane] decatungstate dihydrate ([C₆(MIm)₂]₂W₁₀O₃₂. 2H₂O) as a new family of polyoxometalate-based dicationic ionic liquids (POM-DIL) is synthesized and employed as a novel and powerful heterogeneous catalyst in the synthesis of 4-arylidene-2-phenyl-5(4)-oxazolones (azlactones) under ultrasound-assisted solvent-free condition. On the basis of the results, the products were obtained in excellent yields under mild condition. Utilization of easy work-up and purification make it very interesting from an economic perspective. Moreover, a recycling study confirmed that the catalyst can be reused multiple times without significant loss of its activity.     

A green and selective synthesis of 2‐aryloxazines and 2‐aryltetrahydropyrimidines

An efficient method for the selective synthesis of 2‐substituted oxazines and tetrahydropyrimidines by the reaction of arylnitriles with 3‐amino‐1‐propanol and 1,3‐diaminopropane in the presence of montmorillonite K‐10 and KSF as inexpensive, environmentally benign, and reusable catalysts under classical heating conditions and microwave irradiation is reported. J. Heterocyclic Chem., (2011).     

Sonochemical and visible light induced photochemical and sonophotochemical degradation of dyes catalyzed by recoverable vanadium-containing polyphosphomolybdate immobilized on TiO2 nanoparticles

Na₅PV₂Mo₁₀O₄₀ supported on nanoporous anatase TiO₂ particles, TiO₂–PVMo, was used as an efficient photocatalyst for photocatalytic degradation of different dyes by visible light using oxygen as oxidant. This catalyst showed a good catalytic activity in the sonocatalytic and sonophotocatalytic decomposition of different dyes in aqueous solutions. The TiO₂–PVMo composite showed higher photocatalytic and sonocatalytic activity than pure polyoxometalate or pure TiO₂.