Efficient Oxidation of Alcohols to Carbonyl Compounds by N,N‐Dichloro‐4‐Methylbenzenesulfonamide under Mild Conditions

A number of aldehydes and ketones were prepared by oxidation of alcohol by N,N‐dichloro‐4‐methylbenzenesulfonamide under mild and neutral conditions in good to high yield in dichloromethane at room temperature.     

N,N′,N,N′-TETRABROMO-BENZENE-1,3-DISULFONYLAMIDE AS A NOVEL REAGENT FOR OXIDATIVE AROMATIZATION OF 1,3,5-TRISUBSTITUTED PYRAZOLINES UNDER HETEROGENEOUS AND SOLVENT-FREE CONDITIONS

1,3,5-Trisubstituted pyrazolines were converted to the corresponding pyrazoles in good yields under heterogeneous and solvent-free conditions by N,N′,N,N′-tetrabromo-benzene-1,3-disulfonylamide [TBBDA] at ambient temperature.     

Microwave-Assisted Chemoselective Regeneration of Carbonyl Compounds from Oximes by Silica Chromate/WET SiO2 Under Solvent-Free Conditions

The regeneration of carbonyl compounds from oximes were performed by using silica chromate and wet SiO ₂ (w/w 50%) under microwave irradiation and solvent-free conditions with excellent yields.     

FACILE AND EFFICIENT METHOD FOR DEPROTECTION OF 1,3-OXATHIOLANES WITH N,N′-DIBROMO-N,N′-1,2-ETHANEDIYLBIS(p-TOLUENESULPHONAMIDE)

Aliphatic and aromatic 1,3-oxathiolanes[3pc] are readily oxidized to aldehydes and ketones in good yields under mild conditions by N,N′-dibromo-N,N′-1,2-ethanediylbis(p-toluenesulphonamide) [BNBTS].     

High‐Efficiency Conversion of Trimethylsilyl Ethers to Their Corresponding Ethers using Carbon‐Based Solid Acid as a New Catalyst in Heterogeneous Mixtures

Carbon‐based solid acid was used as a new catalyst for conversion of trimethylsilyl ethers to their corresponding ethers in heterogeneous mixtures. The experiments were done moderately at room temperature, and high yields in suitable times were obtained under these conditions.     

Potentiometric and spectroscopic studies of three new mixed inorganic–organic hybrid materials based on Preyssler and Wells–Dawson heteropolyoxometalates containing proline, leucine, and asparagine

Three new organic–inorganic hybrid materials based on two important heteropolyoxometalates namely Preyssler (=K_12.5H_1.5[Na(H₂O)P₅W₃₀O₁₁₀]·35H₂O) and Wells–Dawson (=K₆[P₂W₁₈O₆₂]·10H₂O) anions, namely, (Hpro)₉(Hleu)₃K₂[Na(H₂O)P₅W₃₀O₁₁₀]·25H₂O (1), (Hpro)₄(Hasp)[HP₂W₁₈O₆₂]·20H₂O (2), and (Hpro)₁₁K₃[Na(H₂O)P₅W₃₀O₁₁₀]·18H₂O (3) where pro, leu, and asp are proline, leucine, and asparagine, respectively, were prepared and identified by elemental analysis, infrared and proton nuclear magnetic resonance spectroscopies, and thermogravimetric analysis. The hybrid materials are made up of positively charged amino acids, [Na(H₂O)P₅W₃₀O₁₁₀]^14? and [P₂W₁₈O₆₂]^6? anions, and H₂O molecules of crystallization. These constituents’ fragments held together into a three-dimensional supermolecular network through non-covalent interactions. The protonation constants of the amino acids used, and Preyssler and Wells–Dawson species in all possible protonated forms, the equilibrium constants for binary systems of proline–asparagine and proline–leucine, and the stoichiometry and stability constants of the corresponding binary and ternary hybrids with Preyssler and Wells–Dawson heteropolyoxometalates in aqueous solution were investigated by potentiometric pH titration method. The stoichiometries of the most hybrid species in solution were compared with the corresponding hybrids in the solid phase, in detail.     

Synthesis,characterization and application of 3‐methyl‐1‐sulfonic acid imidazolium tetrachloroferrate as nanostructured catalyst for the tandem reaction of β‐naphthol with aromatic aldehydes and amide derivatives

3‐methyl‐1‐sulfonic acid imidazolium tetrachloroferrate {[Msim]FeCl₄} was prepared and fully characterized by fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermal gravimetric analysis (TGA), differential thermal gravimetric (DTG), field emission scanning electron microscopy (FESEM), energy dispersive X‐ray analysis (EDX) and vibrating sample magnetometer (VSM) and used, as an efficient catalyst, for the tandem reaction of β‐naphthol with aromatic aldehydes and benzamide at 110 °C under solvent‐free conditions to give 1‐amidoalkyl‐2‐naphthols in high yields and very short reaction times.     

Magnetic‐based picolinaldehyde–melamine copper complex for the one‐pot synthesis of hexahydroquinolines via Hantzsch four‐component reactions

A picolinaldehyde–melamine copper complex was loaded on a magnetic Fe₃O₄ core, so that it contained 0.33 mmol of Cu per gram, and was used as an efficient catalyst. The as‐synthesized catalyst was characterized using various techniques, including Fourier transform infrared spectroscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and thermogravimetric analysis. The catalyst was used to activate the raw materials in the synthesis of hexahydroquinoline derivatives in one‐pot four‐component reactions. Low reaction time (minutes versus half an hour), solvent‐free condition and magnetically separable catalyst are some salient features of the developed catalyst. Also, the optimum amount of catalyst and temperature were determined as 0.07 g and 87.6 °C, respectively, which were obtained using response surface methodology and optimization techniques.     

Some physico-chemical characteristics of amino-acid derivatives containing rest of 1,2,4-triazole-3,4-di-substituted with potential antitumoral activity

Abstract

Dipeptide derivatives from p-aminobenzoyl-phenylglycine and p-aminobenzoyl-phenylalanine were grafted on 1,2,4-triazole heterocycle in order to get new substances with potential biological activity. The compounds synthetized and characterized in this paper have a structure that fits in the antimetabolites category, products used to treat malignant tumors. The presence of several bioactive groups in the same molecule permits us to study the chemical structure - biological activity correlation based on computational analyses using SPARTAN’14 software. Some correlations between the molecular parameters established with Spartan’14 software are evidenced in this paper.     

Resolvent analysis in unbounded flows: role of free-stream modes

Theoretical and Computational Fluid Dynamics - The problem of finding optimal forcing and response for unbounded base flows, exemplified by the Blasius boundary layer, is assessed by means of a...