Liquid-liquid extraction of palladium(II) with N-n-octylaniline from hydrochloric acid media

N-n-Octylaniline in xylene is used for the extractive separation of palladium(II) from hydrochloric acid medium. Palladium(II) was extracted quantitatively with 10 ml of 2% reagent in xylene from 0.5-2 M hydrochloric acid medium. It was stripped from the organic phase with 1:1 ammonia and estimated spectrophotometrically with pyrimidine-2-thiol at 420 nm. The effects of metal ion, acids, reagent concentration and of various foreign ions have been investigated. The method affords binary separation of palladium(II) from iron(III), cobalt(II), nickel(II) and copper(II) and is applicable to the analysis of synthetic mixtures and alloys. The method is fast, accurate and precise.     

Further sesquiterpenes from Polygonum viscosum (Polygonaceae)

Two new sesquiterpenes, 4-methoxycarbonyl-7-(1-methylethyl)-6-oxo-3,3a,7,8,8a-pentahydroazulene-1-carboxylic acid (viscoazusone) and 1,4-dimethoxy-carbonyl-7-(1-methylethyl)-6-oxo-3,3a,7,8,8a-pentahydroazulene (viscoazulone), were isolated from the whole plant of Polygonum viscosum. The structures of these compounds were determined by spectroscopic means.     

Adsorption properties and structure of CO2 adsorbed on open coordination sites of metal-organic framework Ni2(dhtp) from gas adsorption, IR spectroscopy and X-ray diffraction

The microporous metal-organic framework Ni(2)(dhtp) (H(4)dhtp=2,5-dihydroxyterephthalic acid) shows distinct end-on CO(2) coordination to coordinatively unsaturated nickel sites giving rise to high CO(2) adsorption capacity at sub-atmospheric pressures and ambient temperatures.     

Swarnalin and cis-swarnalin, two new tetrahydrofuran derivatives with free radical scavenging activity, from the aerial parts of Cuscuta reflexa

The reversed-phase HPLC analysis of a methanol extract of the aerial parts of Cuscuta reflexa afforded a non-separable mixture (55 : 45) of two novel tetrahydrofuran derivatives, named swarnalin (1) and cis-swarnalin (2), and a known coumarin, 5,6,7-trimethoxycoumarin (3). The structures of the compounds were elucidated unequivocally by UV, HRFABMS and a series of 1D and 2D NMR analyses. The mixture of 1 and 2 showed significant free radical scavenging activity in the DPPH assay and the RC50 value was found to be 3.80 x 10(-4) mg mL(-1) for the mixture, compared to 2.88 x 10(-5) mg mL(-1) for the positive control, quercetin.     

Intramolecular O-H...O hydrogen-bond-mediated reversal in the partitioning of conformationally restricted triplet 1,4-biradicals and amplification of diastereodifferentiation in their lifetimes

The photoreactivity and nanosecond transient phenomena have been investigated for a rationally designed set of ketones 4-9 in order to gain comprehensive insights concerning the influence of intramolecular hydrogen bonding on (i) the lifetimes of triplet 1,4-biradicals and (ii) the partitioning of the latter between cyclization and elimination. Comparisons of the photochemical results and lifetime data for the biradicals of ketones 6 versus 8 and 7 versus 9 revealed a remarkable influence of hydrogen bonding when superimposed upon steric factors: while 6 and 7 yielded cyclobutanols in poor yields, cyclization was found to be overwhelmingly predominant for 8-anti and moderately so for 9-anti, with a high stereoselectivity in the formation of cyclobutanols (>95% for 8-anti). The diastereochemistry in the case of 8 permitted the occurrence of fragmentation or cyclization almost exclusively (>90% cyclization for 8-anti and >75% elimination for 8-syn). Significantly, the intramolecular hydrogen bonding in the biradicals of 8 and 9 was found to reverse their partitioning between cyclization and elimination compared with the behavior of the biradicals of ketones 3; the ketones 8-anti and 9-anti underwent cyclization in benzene, predominantly leading to cyclobutanols with syn stereochemistry between the C2 and C3 substituents. In accordance with photoproduct profiles, an unprecedented approximately 2-fold difference in the lifetimes of the intermediate diastereomeric triplet biradicals of ketones 8 in nonpolar solvents (e.g., tau(syn) = 123 ns and tau(anti) = 235 ns in cyclohexane) was observed via nanosecond laser flash photolysis, while no such difference in lifetimes was found for the triplet biradicals of acetoxy ketones 9. The intriguing diastereodifferentiation in the lifetimes of the diastereomeric triplet 1,4-biradicals of 8 and the product profiles of ketones 6, 7, and 9 are best reconciled via a unified mechanistic picture in which superposition of steric factors over varying magnitudes of O-H...O hydrogen bonding selectively facilitates a particular pathway. In particular, the diastereodifferentiation in the photochemical outcomes for the diastereomers of ketone 8 and in the lifetimes of their triplet biradicals can be understood on the basis of rapid deactivation of the 8-syn triplet biradical via fragmentation and slow cyclization of the 8-anti triplet biradical from chair- and twist-boat-like hydrogen-bonded conformations, respectively. The photolysis in polar aprotic solvents such as DMSO and pyridine was found to reverse the chemoselectivity, yielding reactivity paralleling that of ketones 3, for which the steric factors between the C2 and C3 substituents control the photochemical outcome.     

Thin film of poly(bis[2-(methacryloyloxy)ethyl]phosphate) grafted on surface of poly(ether sulfone) membrane for plutonium(IV)-selective alpha tracks registration in CR-39 detector

Journal of Radioanalytical and Nuclear Chemistry - To impart chemical selectivity in the solid state nuclear track detector based quantification of Pu(IV) ions, a thin film of polymer of...     

Copper(I) complexes of 2-(benzen-1-yl)methyleneamino-3-aminomaleonitrile and triphenylphosphine ligands: synthesis,characterization, luminescence and catalytic properties

Some mixed ligand copper(I) complexes of general formula [Cu(L)(PPh₃)₃]X (X = Cl (1), ClO₄ (2), BF₄ (3) or PF₆ (4); L = 2-(benzen-1-yl)methyleneamino-3-aminomaleonitrile) were prepared and characterized by physicochemical and spectroscopic methods. A single-crystal X-ray diffraction study of [Cu(L)(PPh₃)₃]CIO₄ (2) revealed that the copper atom is four coordinated in a distorted tetrahedral geometry. Electrochemical studies of complexes 1–4 show quasireversible redox behavior corresponding to the Cu(I)/Cu(II) couple. Room temperature luminescence is observed for all four complexes. These complexes proved to be effective catalysts for the Sonogashira coupling of terminal alkynes with aryl halides at 90 °C.     

Rapid and efficient one-pot microwave-assisted synthesis of 2-phenylimidazo[1,2-a]pyridines and 2-phenylimidazo[1,2-a]quinoline in water–PEG-400

An effective, expeditious, environmentally benign one-pot synthesis of 2-phenylimidazo[1,2-a]pyridines and 2-phenylimidazo[1,2-a]quinoline from easily available starting materials as aromatic carbonyl compound, 2-amino pyridine, succinamide, and in situ generated α-iodo acetophenone in combination with green solvent PEG-400 and water (2:1) under microwave irradiation. The newly developed protocol with excellent yield of product in very short time of reaction by avoiding the use of lachrymatric α-chloro and α-bromocarbonyl compounds, volatile, toxic organic and hazardous solvents, reagents is the advantage of this research work. The final products were confirmed by their characterization data such as ¹H NMR, ¹³C NMR, high resolution mass spectrometry (HRMS) and were compared with its reported method.     

Redetermination of ternifoline‐C at 150 K

The relative stereochemistry of ternifoline‐C (7,20‐epoxy‐ent‐kaur‐16‐ene‐1,6,7,15‐tetrol 1‐acetate), C₂₂H₃₂O₆, previously reported by Wu [FudanXuebaoZir. Kex. (1988), 27 , 61–65], has been redetermined at 150 K. The molecular geometry and crystal packing agree well with the previous study.     

High-performance thin-layer chromatography-based method development for the analysis of 4-methoxy-2-nitroaniline as potential genotoxic impurity

JPC – Journal of Planar Chromatography – Modern TLC - Omeprazole contains benzimidazole substitute, and it acts as a proton-pump inhibitor used for gastroduodenal ulcers....