MCM-41-SO3H: an efficient,reusable, heterogeneous catalyst for the one-pot,three-component synthesis of pyrano[3,2-b]pyrans

Research on Chemical Intermediates - MCM-41-SO3H, ordered mesoporous silica material MCM-41 with covalently anchored sulfonic acid groups, was used as a solid acid catalyst for the convenient,...     

An efficient and mild protocol for the synthesis of unsymmetrical ureas in the absence of catalyst and additives

<正>A new practical method for the synthesis of unsymmetrical ureas was achieved by reaction of phenylurea with primary and secondary amines under neutral and mild condition in very good yields.The reaction took place in refluxing dioxane and does not require any catalyst or additives.     

Regioselective synthesis of novel spiroindane-1,3-diones through 1,3-dipolar cycloaddition reactions

A facile synthesis of novel spiroindane-1,3-diones has been achieved via 1,3-dipolar cycloaddition of an azomethine ylide, generated in situ from ninhydrin and 1,2,3,4-tetrahydroisoquinoline, with the conjugated double bond of chalcone derivatives. The regiochemistry and structures of the cycloadducts were determined with spectroscopic data and by X-ray crystal structure analysis.     

Variations in,and Relationships of Surface Area,internal angle of friction and compact diametral fracture strength with degree of compaction

The progress of the compaction process to produce from an assembly of particles a coherent mass can be achieved by the application of shear and normal stress. The achievement of a densified coherent mass necessitates, together with the yielding of material, the movement of particles over and between each other. In uniaxial compaction the angle of internal friction, δ_E, is a projection of the unique critical state line which divides a three dimensional relationship between volume change (V), shear stress (?) and normal stress (σ) into yield domains and surfaces. There is one region for failure and flow (the Hvorslev surface) and another region for failure and consolidation (the Roscoe surface). In this paper the concepts of the Roscoe and Hvorslev surfaces together with the Coulomb yield criterion have been applied to the uniaxial compaction, over a range of compactable stresses, of titanium dioxide (20–2000 kPa). The characteristics of applied and shear stress, angle of internal friction (δ_E), angle of shearing resistance (?) and surface area (S_BET) were measured and correlated with the compaction stress (σ_c) and diametral strength (σ_f) of the compacts to investigate the phenomena of uniaxial compaction.     

Synthesis of Novel Triazole Incorporated Thiazolone Motifs Having Promising Antityrosinase Activity through Green Nanocatalyst CuI-Fe3O4@SiO2 (TMS-EDTA)

In the present work, novel 5-((1-benzyl-1,2,3-triazol-4-yl)methoxybenzylidene)-2-(arylamino)thiazol-4-one thiazolone incorporated triazole derivatives have been designed as tyrosinase inhibitors. The compounds were synthesized through click reaction in good yield. Moreover, the antityrosinas activity of the synthesized derivatives was evaluated. In the search for establishing a click copper-catalyzed azide/alkyne cycloaddition (CuAAC) reaction under strict conditions, in terms of a novel air-stable, a recyclable and efficient magnetic catalyst was planned for new triazole derivatives as a well-organized copper iodide supported on the functionalized Fe₃O₄@SiO₂ core-shell (CuI/Fe₃O₄@SiO₂(TMS-EDTA) nanoparticles). The engineered nanocatalyst synthesized for the first time and characterized by different methods, including FT-IR spectroscopy, XRD, FESEM, EDX, TEM, TGA, and BET analysis. The excellent catalytic performance in ethanol with high surface area (351.7 m²g⁻¹) and short reaction time for diverse functional groups (120–200 min), no use of toxic solvents, reusability of the catalyst, and using eco-friendly conditions are the advantageous of this work. Moreover,the nanocatalyst can be used at least five times without any significant decrease in the yield of the reaction. The thiazolidine-triazole derivatives 9a , 9c , 9e , and 9 g showed promising tyrosinase inhibitory activity with IC₅₀ values in the range of 5.90–9.81 μM. The compounds were found to be considerably more potent tyrosinase inhibitors than the reference inhibitor kojic acid (IC₅₀ = 18.36 μM).     

Copper-catalyzed arylation of phenylurea using KF/Al2O3

A mild and efficient method for the copper-catalyzed arylation of phenylurea is described. The coupling reaction of phenylurea with different functionalized aryl iodides in the presence of air stable CuI, N,N′-dibenzylethylenediamine as a ligand, and KF/Al₂O₃ as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields.     

A dispersive liquid–liquid microextraction based on a task-specific ionic liquid for enrichment of trace quantity of cadmium in water and food samples

In this work, a hydrophilic task-specific ionic liquid (TSIL) of 1-chloroethyl-3-methylimidazolium chloride functionalized with 8-hydroxyquinoline was used in a dispersive liquid–liquid microextraction method followed by flame atomic absorption spectrometry for the enrichment and determination of trace amounts of cadmium (Cd²⁺) ions. The simultaneous chelation and extraction of Cd²⁺ ions was carried out by the TSIL. Fine droplets of the water-immiscible TSIL containing target analyte were generated in situ by addition of an anion exchanger potassium hexafluorophosphate (KPF₆) salt to the sample tube. After phase separation by centrifugation for 4 min, the sedimented TSIL was diluted with acidified ethanol for measurement of Cd²⁺ content. Some significant parameters influence the preconcentration of Cd²⁺ ions such as sample pH, TSIL volume, amount of KPF₆, non-ionic surfactant and salt concentration were investigated. Under the optimal conditions, calibration curve was linear in the range of 5–250 µg L^?1 Cd²⁺ with correlation coefficient of 0.9975 and a detection limit of 0.55 µg L^?1. The relative standard deviation for six replicate measurements of 50 µg L^?1 Cd²⁺ was 1.5%. The method was successfully applied for the extraction and determination of Cd²⁺ ions in water and food samples.     

Novel thermally stable polyimides based on flexible diamine: synthesis, characterization, and properties

A novel diamine with built-in sulfone, ether, and amide structure was prepared via three-step reactions. Nucleophilic reaction of 4-aminophenol with 4-nitrobenzoyl chloride in the presence of propylene oxide led to preparation of N-(4-hydroxy phenyl)-4-nitrobenzamide (HPNB). The nitro group of this compound was reduced with hydrazine and Pd/C to afford 4-amino-N-(4-hydroxy phenyl)benzamide (AHPB). Two moles of AHPB were reacted with bis-(4-chloro phenyl)sulfone to provide a novel sulfone ether amide diamine (SEAD). All the prepared compounds were characterized by common spectroscopic methods. The prepared diamine (SEAD) used to prepare related polyimides by reaction with different aromatic dianhydrides. The obtained poly(sulfone ether amide imide)s were characterized and their properties were studied.     

An efficient procedure for the synthesis of phenacyl and benzyl azolium salts using fluorous alcohols

An efficient procedure for the synthesis of phenacyl and benzyl azolium salts in 2,2,2-trifluoroethanol and 1,1,1,3,3,3-hexafluoroisopropanol as fluorous alcohols have been developed. This synthetic methodology has some advantages with the respect to yield, atom efficiency, solvent and reagents used and wastes generated when compared to the currently in use methods. Using this procedure, a range of phenacyl and benzyl azolium salts can be synthesized with good to excellent yields. The pure salts are separated from the reaction mixture by simple filtration and washing with dry ether.