Substituted pyridines

A number of amides and hydrazides of 4-phenyl-2,5-pyridine dicarboxylic acids are synthesized.     

A mild and efficient synthesis of β-amino alcohols from epoxides using a mesoporous aluminosilicate catalyst

Mesoporous aluminosilicates catalyze efficiently the ring-opening reactions of a range of epoxides with aromatic amines to produce β-substituted alcohols in high yields under mild reaction conditions.     

Size-controlled assembly of gold nanoparticles induced by a tridentate thioether ligand

The ability to control the size and shape of nanoparticle assemblies is essential for the ultimate applications in sensors, catalysis, medical diagnostics, information storage, and quantum computation. This report demonstrates a novel mediator-template strategy toward this ability by exploring molecular driving forces exerted by a tridentate thioether as a mediator and tetraoctylammonium bromide as a templating agent. A combination of the ligand mediation, the surfactant templating, and their relative concentrations served as the driving forces. This combination leads to unprecedented spherical assemblies of gold nanoparticles in controllable sizes via manipulation of the relative concentrations of mediating and templating components.     

An Easy Spectrophotometric Method for the Determination of Hypochlorite Using Thionin

A simple, rapid, and sensitive spectrophotometric method has been developed for the determination of hypochlorite using thionin. The method is based on the reaction of hypochlorite with potassium iodide in acidic medium to liberate iodine. The liberated iodine bleaches the violet color of thionin, which is measured at 600 nm. The decrease in absorbance is directly proportional to the concentration of hypochlorite. Beer’s law is obeyed in the range 0.2– 1.2 µg/mL of hypochlorite. The molar absorptivity, Sandell’s sensitivity, detection limit, and quantitation limit are found to be 1.489 × 10⁴ L/(mol cm), 3.25 × 10⁻³ µg cm⁻², 0.1026 µg/mL, and 0.3112 µg/mL, respectively. The method has been successfully applied to the determination of hypochlorite in various samples of natural water, tap water, milk, etc.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 8, 2005, pp. 798–801.Original English Text Copyright © 2005 by Narayana, Mathew, Vipin, Sreekumar, Cherian.The text was submitted by the authors in English.     

Raman scattering spectra of sodium n-butyl(n-hexyl) phosphate aggregates and conformation about the phosphodiester PO bonds in coagel phases

A new double-chain surfactant molecule, sodium n-butyl(n-hexyl)phosphate (BHP), having an asymmetric molecular structure, has been synthesized. For anhydrous BHP in the solid state and the BHP---H₂O system in the lyotropic liquid crystalline and coagel states, the Raman scattering spectra arising from the accordion vibrational mode were studied in the temperature range −170 to 25°C. For anhydrous BHP, the GG form about the phosphodiester P---O bonds was preferentially stabilized at lower temperature. In the coagel phase of the BHP---H₂O system, preferential stabilization of a specific conformation about the P---O bonds occurred and which molecular form was stabilized was dependent on the water content: for the 8:2 BHP---H₂O sample in the coagel the GT form was stabilized, while for the 7:3 BHP---H₂O coagel sample the TT form was preferentially stabilized. The stabilization of such a specific conformation was also reflected in the higher-frequency region.     

Cyclization of functionalized ketene-N,S-acetals to substituted pyrroles: applications in the synthesis of marine pyrrole alkaloids

α-Oxoketene-N,S-acetals, prepared by the reaction of alkyl glycinates with β-oxodithiocarboxylates followed by alkylation, underwent cyclization in the presence of the Vilsmeier reagent to afford alkyl 3-aryl-4-formyl-5-(alkylsulfanyl)-1H-pyrrole-2-carboxylates in excellent yields. When the reaction was extended to β-oxodithiocarboxylates derived from deoxyanisoin, 3,4-diarylpyrrole-2-carboxylates, the key intermediates in the synthesis of lukianol A and lamellarin Q were formed.     

Indirect complexometric determination of palladium(II) using sodium nitrite as a selective masking reagent

A selective complexometric method is described for the determination of palladium, sodium nitrite being used as masking reagent. Palladium(II) in a given sample solution is initially cornplexed with an excess of EDTA and the surplus EDTA is titrated with zinc sulfate solution at pH 4.5–5.5 (acetic acid-sodium acetate buffer), using xylenol orange as indicator. An excess of sodium nitrite is then added, the mixture is shaken well and the EDTA released from the Pd-EDTA complex is titrated with a standard zinc sulfate solution. Results are obtained for 2.5–27.5 mg of Pd with relative errors 0.5% and standard deviations 0.05 mg. The interferences of various ions are studied. The method is applied for the determination of palladium(II) in alloys and complexes.     

Suitability of commercial colloids for magnetic hyperthermia

Commercial nanoparticles supplied by Chemicell, Micromod and Bayer-Schering were characterised with regard to their nanocrystalline diameter, hydrodynamic diameter, total iron content and relative ferrous iron content. Additionally, calorimetric measurements were taken using a 900 kHz AC magnetic field of amplitude 5.66 kA/m. It was found that those samples containing relatively high (>18%) ferrous content generated a substantially smaller (12% on average) intrinsic loss power (ILP) than those samples with a lower ferrous content. Two nominally identical Chemicell samples that differed only in their production date showed significantly different ILPs, attributed to a variation in batch-to-batch crystallite sizes. The highest ILP values in the cohort, ca. 3.1 nHm²/kg, were achieved for particles with hydrodynamic diameters of ca. 70 nm and nanocrystalline diameters of ca. 12 nm. These compare favourably with most samples prepared in academic laboratories, although they are not as high as the ca. 23.4 nHm²/kg reported for naturally occurring bacterial magnetosomes.     

Mesoporous aluminosilicate promoted protection and deprotection of carbonyl compounds

Mesoporous aluminosilicates are efficient heterogeneous catalysts for both the formation and hydrolysis of a range of acetals under mild conditions and in short reaction times.