Ionic liquid promoted one-pot synthesis of 3-aminoimidazo[1,2-a]pyridines

3-Aminoimidazo[1,2-a]pyridines have been synthesized in good to excellent yields in the presence of the ionic liquid 1-butyl-3-methylimidazolium bromide [bmim]Br, the reaction workup is simple and the ionic liquid can be easily separated from the product and reused.     

Nano-SiO2 catalyzed three-component preparations of pyrano[2,3-d]pyrimidines, 4H-chromenes,and dihydropyrano[3,2-c]chromenes

An efficient one-pot three-component procedure has been developed for the preparation of tetrahydrobenzo[b]pyrans, dihydropyrano[3,2-c]chromenes, and pyrano[2,3-d]pyrimidines using nano-SiO₂ as catalyst in H₂O at 70 °C. This methodology has a number of advantages such as: use of reusable catalyst, easy access, short reaction times, high yields, easy work up and use of non-toxic and green solvent.     

Transport properties of methane,ethane, propane, <Emphasis Type="Italic">iso</Emphasis>-butane and <Emphasis Type="Italic">neo</Emphasis>-pentane from ab initio potential energy surfaces

In this work, the potential energy surfaces for methane, ethane, propane, iso-butane and neo-pentane, obtained from the ab initio calculations via different levels of electron-correlation, were used in the framework of the kinetic theory to calculate the transport collision integrals and their corresponding low-density transport coefficients. The theoretical results are compared with the available experimental data and the effective scaling potential parameters of methane, ethane, propane, iso-butane and neo-pentane along with the kinetic theory collision integrals and higher order correction factors were obtained. Relation between different potentials and kinetic theory collision integrals are discussed and it was shown that the Mason–Monchick approach is a reliable approximation in the calculation of diffusion coefficients and shear viscosities of chain alkanes, whereas the full predictive Boltzmann weighting method is successful only for lighter alkanes, such as methane and ethane.     

An Efficient Route to Pyridazino[4, 3‐e][1, 3, 4]thiadiazines

Some new 3‐(alkylsulfanyl)‐7‐chloro‐1‐phenyl‐1H‐pyridazino [4,3‐e][1,3,4]thiadiazine were synthesized by treatment of the alkyl‐2‐phenylhydrazinecarbodithioates with 4‐bromo‐3,6‐dichloropyridazine in alkaline acetonitrile. Orientation of the reaction has been determined by X‐ray crystallography technique. The chlorine atom on the number 7 position of these products was replaced by secondary amines at reflux condition.     

Cellulose whiskers reinforced polyvinyl alcohol copolymers nanocomposites

Nanocomposite materials were prepared from copolymers of polyvinyl alcohol and polyvinyl acetate and a colloidal aqueous suspension of cellulose whiskers prepared from cotton linter. The degree of hydrolysis of the matrix was varied in order to vary the hydrophilic character of the polymer matrix and then the degree of interaction between the filler and the matrix. Nanocomposite films were conditioned at various moisture contents, and the dynamic mechanical and thermal properties were characterized using dynamic mechanical analysis and differential scanning calorimetry, respectively. Tensile tests were performed at room temperature to estimate mechanical properties of the films in the non linear range. All the results show that stronger filler/matrix interactions occur for fully hydrolyzed PVA compared to partially hydrolyzed samples. For moist samples, a water accumulation at the interface was evidenced. The reinforcing effect was found to be all the higher as the degree of hydrolysis of the matrix was high.     

Poly(ortho‐toluidine) Modified Carbon Paste Electrode: A Sensor for Electrocatalytic Reduction of Nitrite

The electrocatalytic reduction of nitrite has been studied by poly(ortho‐toluidine) films modified carbon paste electrode (P‐OT/MCPE). Cyclic voltammetry and chronoamperometry techniques were used to investigate the suitability of poly(ortho‐toluidine) as a mediator for the electrocatalytic nitrite reduction in aqueous solution with various pH. Results showed that pH 0.00 is the most suitable for this purpose. In the optimum pH, the reduction of nitrite occurs at a potential about 600 mV more positive than unmodified carbon paste electrode. The catalytic reaction rate constant, (k_h), was calculated 8.68×10² M^?1 s^?1 by the data of chronoamperometry. The catalytic reduction peak current was linearly dependent on the nitrite concentration and the linearity range obtained was 5.00×10^?4 M–1.90×10^?2 M. Detection limit has been found to be 3.38×10^?4 M (2σ). This method has been successfully employed for quantification of nitrite in real sample.     

Synthesis of New Multibenzo Oxygen–Sulfur Donor Macrocycles Containing Lactams at Room Temperature

Some new oxygen–sulfur, multibenzo macrocyclic ligands containing amide groups have been prepared using the macrocyclization process with the reaction of 2,2′-thiobis-[4-methyl(2-aminophenoxy)phenyl ether] as a symmetrical diamine with appropriate dicarboxylicacid dichlorides in moderate yields. This macrocyclization led to the formation of di- and tetramide macrocycles. These reactions were routinely carried out at ambient temperature in CH₂Cl₂ as solvent in high dilution without template effect conditions. It is found that sulfur the atom affects the rigidity of the macrocycles and diastereotopicity of nuclei in the ring of these series of macrocyclic compounds.     

以淀粉溶液为催化剂一锅三组分法合成四氢苯并[b]吡喃和3,4-二氢吡喃并[c]苯并吡喃衍生物(英文)

Tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives were synthesized via a one-pot three-component condensation of aromatic aldehydes with malononitrile and dimedone or 4-hydroxycoumarin in excellent yields in the presence of starch solution as a highly efficient homogenous catalyst.The use of a nontoxic and biodegradable catalyst,simple work-up procedure,and short reaction time are advantages of this method.