Nano palladium supported on high‐surface‐area metal–organic framework MIL‐101: an efficient catalyst for Sonogashira coupling of aryl and heteroaryl bromides with alkynes

Palladium nanoparticle‐incorporated metal–organic framework MIL‐101 (Pd/MIL‐101) was successfully synthesized and characterized using X‐ray diffraction, nitrogen physisorption, X‐ray photoelectron, UV–visible and infrared spectroscopies, and transmission electron microscopy. The characterization techniques confirmed high porosity and high surface area of MIL‐101 and high stability of nano‐size palladium particles. Pd/MIL‐101 nanocomposite was investigated for the Sonogashira cross‐coupling reaction of aryl and heteroaryl bromides with various alkynes under copper‐free conditions. The reusability of the catalyst was tested for up to four cycles without any significant loss in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Experimental investigation on the thermophysical properties of beryllium oxide-based nanofluid and nano-enhanced phase change material

Journal of Thermal Analysis and Calorimetry - Low thermal conductivity is a primary issue in the development of efficient heat transfer fluids and materials required for the thermal management of...     

Rapid and efficient synthesis of optically active pyrazoles under solvent-free conditions

2-Formyl glycals undergo rapid condensation with arylhydrazines under solvent-free conditions to give the corresponding optically pure 4-substituted pyrazoles in good yields with high selectivity. The stereochemistry of the products was assigned by various NMR experiments.     

Friedel-Crafts alkylation of indoles with epoxides catalyzed by nanocrystalline titanium(IV) oxide

Friedel-Crafts alkylation of indoles with epoxides to afford 3-alkyl indole derivatives at room temperature with moderate to good yields and high regioselectivity using nanocrystalline titanium(IV) oxide catalyst is described.     

Construction of spiro[5.5]undecanes containing a quaternary carbon atom adjacent to a spirocentre via an Ireland ester Claisen rearrangement and RCM reaction sequence. Total syntheses of (±)-α-chamigrene, (±)-β-chamigrene and (±)-laurencenone C

Starting from cyclohexanecarboxylic acid, a combination of an Ireland ester Claisen rearrangement and RCM reactions was exploited for an efficient construction of spiro[5.5]undecanes containing a quaternary carbon atom adjacent to the spirocentre and the methodology was extended to complete total syntheses of three chamigrenes.     

CAN mediated cyclization of epoxypropyl cinnamyl ethers: a facile stereoselective synthesis of tetrahydropyran derivatives

Cerium(IV) ammonium nitrate in substoichiometric amounts, promotes the intramolecular cyclization of epoxypropyl cinnamyl ethers to the corresponding 3,4,5-trisubstituted tetrahydropyran derivatives in moderate to good yields.     

Second Dissociation Constant of Bis-[(2-hydroxyethyl)amino]acetic Acid (BICINE) and pH of Its Buffer Solutions from 5 to 55 °C

The values of the second dissociation constant, K ₂, and related thermodynamic quantities of the ampholyte bis[(2-hydroxyethyl)amino]acetic acid (BICINE) have been determined at temperatures from 5 to 55 ^∘C. The pH values of six equimolal buffer solutions, and four buffer solutions having ionic strengths (I = 0.16 mol⋅kg⁻¹) similar to those in blood plasma, have been evaluated at 12 temperatures from 5 to 55 ^∘C using the Bates–Guggenheim convention. The liquid junction potentials (E _j ) between the buffer solutions of BICINE and saturated KCl solution of the calomel electrode at 25 and 37 ^∘C have been estimated by measurement with a flowing junction cell. These values of E _j have been used to ascertain the operational pH values at 25 and 37 ^∘C. The pK ₂ values at 25 and 37 ^∘C are 8.333 and 8.156, respectively. The thermodynamic quantities associated with the second acid dissociation have been calculated from the values of pK ₂ as a function of temperature. The zwitterionic buffer BICINE was shown to be useful as a pH standard in the region close to that of blood serum.     

Second Dissociation Constants of 4-[N-morpholino]butanesulfonic Acid and N-[2-hydroxyethyl]piperazine-N′-4-butanesulfonic Acid from 5 to 55°C

The values of the second dissociation constant, pK ₂, for the dissociation of the NH⁺ charge center of the zwitterionic buffer compounds 4-(N-morpholino)butanesulfonic acid (MOBS), and N-(2-hydroxyethyl)piperazine-N-4-butanesulfonic acid (HEPBS) have been determined from 5 to 55°C, including, 37°C at intervals of 5°C. The electromotive-force (emf) measurements have been made utilizing hydrogen electrodes and silver–silver chloride electrodes. The value of pK ₂ for MOBS was found to be 7.702 ± 0.0005, and 8.284 ± 0.0004 for HEPBS, at 25°C, respectively. The related thermodynamic quantities, G ^o, H ^o, S ^o, and C _p ^o for the dissociation processes of MOBS and HEPBS have been derived from the temperature coefficients of pK ₂. Both the MOBS and HEPBS buffer materials are useful as primary pH standards for the control of pH 7.3 to 8.6 in the region close to that of physiological fluids.     

Development and Validation of a Liquid Chromatographic Method for Determination of Efavirenz in Human Plasma

A simple, rapid, and sensitive high-performance liquid chromatographic method for estimation of efavirenz in human plasma has been developed and validated. Chromatography was performed with C₁₈ analytical column and 50:50 acetonitrile–phosphate buffer (pH 3.5) as mobile phase. Compounds were monitored by UV detection at 247 nm. The retention time for efavirenz was 6.45 min and that for the internal standard, nelfinavir, was 2.042 min. Response was a linear over the concentration range of 0.1 μg–10 μg mL⁻¹ in human plasma. The method was simple, specific, precise and accurate and was useful for bioequivalence and pharmacokinetic studies of efavirenz.     

A versatile and practical synthesis of bis(indolyl)methanes/bis(indolyl)glycoconjugates catalyzed by trichloro-1,3,5-triazine

A practical and efficient electrophilic substitution reaction of indoles with a variety of aldehydes was carried out using catalytic trichloro-1,3,5-triazine (10 mol %) in acetonitrile to furnish the corresponding bis(indolyl)methanes in excellent yields. Similarly, sugar derived aldehydes gave hitherto unknown bis(indolyl)glycoconjugates in very good yields.