A simple highly versatile and efficient sonochemical synthesis of 1,2,4,5-tetrasubstituted and 2,4,5-trisubstituted imidazoles is achieved by condensation of 1,2-dicarbonyl compound, aldehyde, ammonium acetate and primary amine using antimony trichloride immobilized on silica gel (SiO2-OSbCl2) as a catalyst in ethanol at moderate temperature. Operational simplicity, practicability and applicability to various substrates make this method an interesting […]
Reaction between aromatic aldehydes and 3–methyl-1-phenyl-2-pyrazoline-5-one catalyzed by nano-SiO2/HClO4 in water under reflux provided a simple and efficient route for the synthesis of 4-((5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)(aryl)methyl)-3-methyl-1-phenyl-1H-pyrazol-5-ol derivatives in high yields.
The thermodynamic of the known and very effective catalytic system, hydrogen peroxide (H2O2) and methyltrioxorhenium (MTO) is studied in different solvents using UV-Visible spectroscopic method. The thermodynamic parameters (ΔG, ΔH and ΔS) for two equilibrium reactions, MTO + H2O2 ⇌ A + H2O and A + H2O2 ⇌ B.H2O (A, [MeRe(O)2(O2)]; B.H2O, [MeRe(OH2)(O)(O2)2]), are determined. […]
Effects of water on the catalytic performances of MoVTeNbO catalyst in the oxidation of propane to acrylic acid have been investigated at different reaction temperatures and different steam contents. Obtained results show that both catalytic performances and catalyst structure are very sensitive to the presence of water vapor in the reaction feed. Presence of water […]
An efficient and simple procedure for the synthesis of 1,8-dioxo-octahydroxanthenes from the aromatic aldehydes and 5,5-dimethylcyclohexane-1,3-dione (dimedone) in the presence of boric acid [BO3H3 or B(OH)3] as an inexpensive and reusable catalyst is described. The salient features of this methodology are: the elimination of corrosive liquid acids, high yields, simple methodology, short reaction times, easy […]
Silica-bonded n-propyldiethylenetriamine sulfamic acid (SBPDSA) was found as an efficient solid acid for the synthesis of coumarins. Coumarin derivatives were obtained via the Pechmann condensation reaction of phenols and β-keto-esters at 80 oC under solvent-free conditions. Also, biscoumarins were obtained via the condensation of aldehydes and 4-hydroxycoumarin in water at reflux conditions. The heterogeneous solid […]
The Brønsted acidic ionic liquid ([BMIm]HSO4) catalyzed three-component synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives at room temperature. The integrity of the ionic liquid remains reasonably unchanged when it is separated from the reaction mixture by water extraction, as it can be recycled several times without any loss of activity in each of the title syntheses. The products […]
Suzuki cross-coupling reaction of different aryl halides with arylboronic acids was successfully carried out in methanol using ortho-palladated complex of 2-methoxyphenethylamine. All substrates afforded the corresponding products in good to high yields in the presence of low amounts of this complex as efficient and active catalyst. Application of microwave irradiation improved the yields of the […]
A simple and mild procedure for the conversion of anilines into aryl isocyanates is described using the 3-hydroxypropylammonium acetate (HPAA) ionic liquid as a novel and efficient media has been explored in the synthesis of aryl isocyanates from the reaction of substituted urea with sodium nitrite in a water immiscible solvent. This ionic liquid can […]
2,4-dinitrophenylhydrazanomethylphenol (DNPHMP) was immobilized onto silicate rice husk ash to form a heterogeneous catalyst denoted as RHDNPH. The elemental and EDX analysis of RHDNPH showed the nitrogen is incorporated into silica. The RHDNPH had 154.6 m2g-1 as a specific surface area. The FT-IR clearly showed the appearance of –NH and C=N absorption band at the […]
In this paper, we used quantum chemical approach to shed light on the catalytic mechanism of γ-carbonic anhydrase (γ-CA) to convert carbon dioxide to bicarbonate ion. Density functional theory (DFT) using B3LYP and UB3LYP functional and three split-valance including 6-31G*, 6-311G** and 6-311++G** basis sets were used to calculate the details of electronic structure and […]
A variety of alcohols readily add to 3,4-dihydro-2H-pyran under solvent free conditions in the presence of catalytic amount of acidic ionic liquid [Et3N(CH2)4SO3H][OTs] to afford the corresponding tetrahydropyranyl ethers in good to excellent yields at room temperature. The use of this procedure allows easy separation of the desired products from ionic liquid and recycling the […]