A modified procedure for the Dakin-West reaction: an efficient and convenient method for a one-pot synthesis of β-acetamido ketones using silica sulfuric acid as catalyst

A one-pot, four-component condensation of an aryl aldehyde, an aryl ketone, acetyl chloride and acetonitrile in the presence of silica sulfuric acid as an active, inexpensive, recoverable and recyclable catalyst is disclosed for the synthesis of β-acetamido ketones.     

Biomimetic Alkene Epoxidation and Alkane Hydroxylation with Sodium Periodate Catalyzed by Mn(III)-salen Supported on Amberlite IRA-200

Summary. The Mn(III)-salen, containing phosphonium groups at the 5,5′-positions of the salen ligand supported on Amberlite IRA-200 via electrostatic binding was used for the oxidation of alkenes and alkanes with sodium periodate at room temperature in the presence of imidazoles as axial ligands, and the effect of solvent, different axial ligands, and various oxygen donors was investigated. This heterogenized catalyst shows high catalytic activity in alkene epoxidation and alkane hydroxylation. It showed high selectivity in the epoxidation of stilbenes, α-pinene, and (R)-(+)-limonene, and exhibits a particular ability to epoxidize linear alkenes. The stability and reusability of this new heterogenized metallo-salen complex was also investigated. The catalyst was characterized by FTIR, UV-Vis, SEM, and thermal analysis.     

Synthesis and X-ray crystal structures of some isothiosemicarbazone complexes

Transition Metal Chemistry - Four complexes of a new isothiosemicarbazone ligand have been prepared and characterized as μ2-pip-(NiL)2 (1), MnL2 (2), UO2L(BrSal)BuOH (3) and (μ2-MoO2L)2...     

Empirical correlations development for heat transfer and friction factor of a solar rectangular air passage with spherical-shaped turbulence promoters

Journal of Thermal Analysis and Calorimetry - A study was conducted to enhance the thermo-hydraulic performance of a rectangular solar air passage with integrated spherical-shaped turbulence...     

An organic‐inorganic heterogeneous catalyst based on Keplerate polyoxometalates for oxidation of dibenzothiophene derivatives with Hydrogen peroxide

An organic‐inorganic material (NH₄)₂(MimAM)₄₀[Mo₁₃₂O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] have been synthesized by reacting [(NH₄)₄₂[Mo^VI₇₂ Mo^V₆₀O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] with the ionic liquid 3‐Aminoethyl‐1‐methylimidazolium bromide. The catalyst showed remarkably a high catalytic performance in the oxidation of dibenzothiophene (DBT) derivatives with H₂O₂ 35% as a safe and green oxidant. The main parameters affecting the process including catalyst, acid additive, hydrogen peroxide amounts and temperature have been investigated in detail. Sulfur removal of DBT in n‐heptane reached to 98.3% yield at 40 °C using 2.5 mmol H₂O₂ and 100 mg of (NH₄)₂(MimAM)₄₀[Mo₁₃₂O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] after 90 min. Under the optimal conditions, BT (benzothiophene), DBT (dibenzothiophene) and 4,6‐DMDBT (4,6‐dimethyl‐dibenzothiophene) achieved high desulfurization efficiency. Our results showed that the reactivity order of different model sulfur compounds are thiophene <4,6‐dimethyl dibenzothiophene< dibenzothiophene. The catalysts could be easily separated from the reaction solution by simple filtration and recycled for several times without loss of activity.     

The Exterior Degree of a Pair of Finite Groups

The exterior degree of a pair of finite groups (G, N), which is a generalization of the exterior degree of finite groups, is the probability for two elements (g, n) in (G, N) such that g ? n = 1. In the present paper, we state some relations between this concept and the relative commutatively degree, capability and the Schur multiplier of a pair of groups.     

Protection of Alcohols and Phenols with Dihydropyran and Detetrahydropyranylation by ZrCl4

Alcohols and Phenols are protected efficiently with dihydropyran(DHP) in the presence of catalytic amounts of zirconium tetrachloride in dichloromethane. Deprotection of THP-ethers is also afforded in a methanolic solution at room temperature.     

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

Summary. 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.     

Electron‐deficient vanadium(IV) tetraphenylporphyrin: A new,highly efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane

In the present work, the application of electron‐deficient tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V^IV(TPP)(OTf)₂], in the trimethylsilylation of alcohols and phenols with hexamethydisilazane (HMDS) is reported. This new V(IV) catalyst was used as an efficient catalyst for silylation of not only primary alcohols but also sterically hindered secondary and tertiary alcohols with HMDS. Trimethylsilylation of phenols with HMDS was also performed to afford the desired Trimethylsilyl ethers (TMS) ethers. The chemoselectivity of this method was also investigated. This catalyst can be reused several times without loss of its activity. Copyright © 2011 John Wiley & Sons, Ltd.