Oxidation of Aromatic Amines to Quinones by Iodic Acid under Microwave Irradiation in the Presence of Montmorillonite K10 and Silica Gel

A variety of aromatic amines are oxidized to their corresponding quinones in excellent yields by supported iodic acid under microwave irradiation and solvent free conditions.     

The effect of 3D printing on the morphological and mechanical properties of polycaprolactone filament and scaffold

Three‐dimensional (3D) printing becomes an attractive technique to fabricate tissue engineering scaffolds through its high control on fabrication and repeatability using the printing parameters. This technique can be combined by the finite element method (FEM), and tissue‐specific scaffolds with desirable morphological and mechanical properties can be designed and manufactured. In this study, the influential 3D printing parameters on the morphological and mechanical properties of polycaprolactone (PCL) filament and scaffold were studied experimentally and numerically. First, the effects of printing parameters and process on the properties of extruded PCL filament were investigated. Then, using FEM, the effects of filament specifications on the overall characteristics of the scaffold were evaluated. Results showed that both the printing process in terms of resting time and remaining time and the printing parameters like pressure, printing speed, and printing path length have influenced the filament properties. In addition, both the filament diameter and elastic modulus had significant effects on the properties of scaffold especially, a 20% increase in the filament diameter caused the scaffold compressive elastic modulus to rise by around 72%. It is concluded that the printing parameters and process must be tuned very well in fabricating scaffolds with the desired morphology and mechanical property.     

A green and efficient oxidation of benzylic alcohols using H2O2 catalyzed by montmorillonite K-10 supported CoCl2

Primary and secondary benzylic alcohols were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H2O2 catalyzed by montmorillonite K-10 supported cobalt（Ⅱ） chloride.     

Cup-shaped E,E-stilbenophane: synthesis,crystal structure and supramolecular chemistry

A new E,E-stilbenophane was synthesised and characterised. The crystal structure of this cyclophane shows that this molecule has a cup-shaped structure, which hosts a phenyl ring of neighbouring molecule as guest in its cavity with a π–π distance of about 3.7 Å. Moreover, the NMR spectra and theoretical analysis (gauge-independent atomic orbitals (GIAO) and quantum theory of atoms in molecules (QTAIM)) suggest that the silver recognition by E,E-stilbenophane host molecules is based on cation–π interactions in which the π-electrons of the double bonds play a major role.     

Pd-Cu–Mediated Synthesis of 2-Substituted Imidazo[1,2-α]pyridines in Water

The reaction of 2-amino-1-(2-propynyl)pyridinium bromide with various iodobenzenes, catalyzed by Pd-Cu, in the presence of sodium lauryl sulfate as the surfactant and cesium carbonate as the base, in water, leads to the formation of 2-substituted imidazo[1,2-α]pyridines.     

Preparation and some properties of a polyethyleneimine-agarose metal adsorbent

An adsorbent for metal ions has been prepared by reacting high molecular weight polyethyleneimine (PEI) with a crosslinked and activated agarose gel, Novarose. The synthesis variables, i.e. time, temperature, pH, PEI concentration and PEI/Novarose ratio, were optimized in order to obtain a high metal binding capacity of the adsorbent. The binding capacity for Cu(2+) is 500 micromol/ml packed adsorbent. A number of properties of the adsorbent relevant for metal ion accumulation has been investigated for Cu(2+), Ni(2+), Cd(2+) and Zn(2+). Adsorption capacities, adsorption isotherms, distribution coefficients, recoveries and relative rates of accumulation were determined. The adsorbent can be used for preconcentration and for separation of interfering alkali and alkaline earth metals in analytical applications.     

Synthesis, spectroscopy, electrochemistry and thermal study of vanadyl tridentate Schiff base complexes: theoretical study of the structures of compounds by ab initio calculations

The VO(IV) complexes of tridentate ONN Schiff ligands were synthesized and characterized by IR, UV–Vis and elemental analysis. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron-withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeO < H < Br < NO₂. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the VO(IV) complexes were carried out in the range of 20–700 °C. The VOL¹(OH₂) and VOL²(OH₂) decomposed in three steps, whereas the VOL³(OH₂) and VOL⁴(OH₂) complexes decomposed in two steps. The thermal decomposition of these complexes is closely related to the nature of the Schiff base ligands and proceeds via first-order kinetics. The structures of compounds were determined by ab initio calculations. The optimized molecular geometry and atomic charges were calculated using MP2 method with 6-31G(d) basis. The results suggested that, in the complexes, V(IV) ion is in square-pyramid N₂O₃ coordination geometry. Also the bond lengths and angles were studied and compared.     

A convenient and regioselective oxidative bromination of electron-rich aromatic rings using potassium bromide and benzyltriphenylphosphonium peroxymonosulfate under nearly neutral reaction conditions

Regioselective oxidative bromination of electron-rich aromatic rings has been studied using potassium bromide as a bromine source in the presence of benzyltriphenylphosphonium peroxymonosulfate as oxidant under nearly neutral reaction conditions. In most cases we obtained monobrominated derivatives regioselectively and in good to high yields without the aid of strong acids.