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.     

Tris(2-ethylhexyl)phosphate as an extractant for trivalent gallium, indium and thallium

A systematic study of solvent extraction behaviour of gallium(III), indium(III) and thallium(III) with tris(2-ethylhexyl)phosphate from salicylate media has been undertaken and a scheme for their separation is proposed. The optimum extraction conditions are evaluated and described. The method is applicable to the analysis of standard aluminium and aluminium alloys samples. The results obtained are reproducible and accurate.     

Microwave-assisted "libraries from libraries" approach toward the synthesis of allyl- and C-cyclopropylalkylamides

Cascade reactions of internal and terminal alkynes, zirconocene hydrochloride, dimethylzinc, and phosphinoyl imines (prepared in one step from aldehydes and diphenylphosphinoyl amide) lead to allylic phosphinoyl amides after aqueous workup. Microwave acceleration allows the completion of this one-pot reaction sequence in 10 min. These allylic amides can be converted into a variety of derivatives, including carbamates and sulfonamides, or reacted prior to workup with diiodomethane to give novel C-cyclopropylalkylamides. A solution-phase "libraries from libraries" approach was used to generate an intermediate 20-member library which was subsequently expanded to a 100-member library by a series of N-functionalizations. The biological activity was evaluated in an assay for competitive binding to the estrogen receptor (ERalpha), revealing three potent lead compounds of a new structural type.     

Photocatalysed eosin Y mediated C(sp3)-H alkylation of amine substrates via direct HAT

A visible light promoted, photoredox catalysed, green one-pot approach for the alkylation of amine substrates with sp² carbon has been developed. This eosin Y based organic transformations, can behave as an effective direct hydrogen-atom transfer catalyst for coupling reaction. The proposed strategy includes simple procedure which can make adduct product with sp² carbon. This eosin Y based photocatalytic hydrogen-atom transfer strategy may hold great potential for diverse functionalization of a wide range of native CH bonds in an economical and sustainable manner.     

An extraction study of gallium, indium and thallium using TPASO as an extractant

A method is proposed for the extraction and individual separation of trivalent gallium, indium and thallium from salicylate media using triphenylarsine oxide dissolved in toluene as an extractant. The optimum extraction conditions are evaluated and described. The extracted metal ions are stripped and estimated spectrophotometrically following complexation with 4-(2-pyridylazo) resorcinol. A possible mechanism of the extraction is discussed. The method permits rapid and precise individual separation of gallium (III), indium (III) and thallium (III) and is applicable to the analysis of alloy samples.     

A new algorithm for minimizing convex functions over convex sets

Let be a convex set for which there is an oracle with the following property. Given any pointz∈ℝ ⁿ the oracle returns a “Yes” ifz∈S; whereas ifz∉S then the oracle returns a “No” together with a hyperplane that separatesz fromS. The feasibility problem is the problem of finding a point inS; the convex optimization problem is the problem of minimizing a convex function overS. We present a new algorithm for the feasibility problem. The notion of a volumetric center of a polytope and a related ellipsoid of maximum volume inscribable in the polytope are central to the algorithm. Our algorithm has a significantly better global convergence rate and time complexity than the ellipsoid algorithm. The algorithm for the feasibility problem easily adapts to the convex optimization problem.     

Synergetic extraction and spectrophotometric determination of iron (II) in steel

Summary A simple and rapid method is described for synergetic extraction and spectrophotometric determination of iron(II). The Fe(II)--furildioxime-pyridine complex extracted into chloroform has a characteristic pink color measurable at 570 nm. Iron is also separated from associated elements and the results of the analysis of synthetic mixtures and standard steel samples are reported.

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Zusammenfassung Eine einfache und rasche Methode zur Extraktion und Bestimmung von Eisen(II) wurde beschrieben. Der Komplex Fe(II)--Furildioxim-Pyridin wird mit Chloroform extrahiert. Seine charakteristische rosa Farbe ist bei 570 nm meßbar. Eisen läßt sich so auch von Begleitelementen trennen. Die Analysenergebnisse für synthetische Gemische und Standard-Stahlproben werden mitgeteilt.

     

Rapid microwave-assisted liquid-phase combinatorial synthesis of 2-(arylamino)benzimidazoles

An efficient, facile, and practical liquid-phase combinatorial synthesis of benzimidazoles under microwave irradiation is described. In the first step of reaction sequence, polymer-bound activated aryl fluoride was condensed with selective primary amines via an ipso-fluoro displacement reaction. Reduction of the polymer-bound nitro group followed by cyclization with isothiocyanates afforded immobilized benzimidazoles. The desired products were obtained in high yield with high purity after detaching from the soluble matrix. All reactions involved (S(N)Ar reaction, reduction, cyclization, and support cleavage) were performed completely within a few minutes under microwave irradiation. The coupling of microwave technology with liquid-phase combinatorial synthesis constitutes a novel and particularly attractive avenue for the rapid generation of structurally diverse libraries.     

Liquid-liquid extraction of tungsten(VI) with mesityl oxide application to an alloy steel

A new and simple method has been developed for the rapid extraction of tungsten(VI) with mesityl oxide. Quantitative extraction occurs from solutions 1M in hydrochloric acid and 12M in lithium chloride (as the salting-out agent) with 75% mesityl oxide in isobutyl methyl ketone. Tungsten is finally determined photometrically as the thiocyanate complex in the aqueous phase. Tungsten-(VI) can be extracted and determined satisfactorily in the presence of several elements. The method is shown to be applicable to an alloy steel.     

Liquid-liquid extraction and separation studies of yttrium

A simple selective method is presented for the solvent extraction of yttrium from salicylate media by using triphenylphosphine oxide. Yttrium is extracted quantitatively from 0.05 mol/l sodium salicylate solution at pH 4.5–5.0 using 1.8% triphenylphosphine oxide dissolved in toluene as an extractant and can be subsequently stripped using water and determined spectrophotometrically with Thoron-I. This precise and accurate method permits the separation of Y from Sc, Ti, V, Cr, Fe, Zr, Hf, Th and U from binary mixtures and multi-component systems. Received: 17 January 1995 / Accepted: 12 May 1995