Ammonium salt catalyzed multicomponent transformation: simple route to functionalized spirochromenes and spiroacridines

The combination of isatin or acenaphthoquinone, an activated methylene reagent, and 1,3-dicarbonyl compounds in the presence of catalytic ammonium chloride was found to be a suitable and efficient method for the synthesis of the biologically important spirooxindoles.     

Modification of a steel fiber with a graphene based bucky gel for headspace solid-phase microextraction of volatile aromatic hydrocarbons prior to their quantification by GC

A graphene based bucky gel-coated stainless steel fiber was prepared and applied to headspace solid phase microextraction of volatile organic compounds. Graphene was mixed with an ionic liquid to produce a bucky gel that displays the attractive features of both compounds. It can be directly deposited on an etched stainless steel wire to give the fiber for use in extraction of benzene, toluene, ethylbenzene and xylene (BTEX) isomers. The presence of graphene favors the π-interaction between the sorbent and aromatic analytes. The sorbent is thermally stable up to 300 °C and can be used more than 50 times. It was characterized by field emission scanning electron microscopy, FT-IR spectroscopy and thermogravimetric analysis. Under optimized conditions, linear responses were found in the range of 0.11–5000 μg L^?1 for toluene, 0.15–5000 for benzene and o-xylene, 0.17–5000 for m- and?p-xylene and 0.20–5000 for ethylbenzene. Limits of detection are between 0.03 and 0.06 μg L^?1 (at an S/N ratio of 3). The run-to-run RSDs are <5.8% (for n =?6), and fiber-to-fiber RSDs are 4.1–9.2% (n =?4). The method was successfully applied to the extraction of BTEX isomers in spiked urine samples and gave recoveries between 88 and 105%.

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Graphical abstract Graphene based bucky gel (G-BG) was prepared by mixing an ionic liquid with graphene. It was physically deposited on stainless steel wire. The fiber was applied to the headspace solid phase microextraction (HS-SPME) of benzene, toluene, ethylbenzene and xylenes.

     

Preparation and Characterization of Carbon Nanotubes Supported Ni2P for Hydrodesulfurization (HDS) of Naphtha

Abstract

Ni₂P nanoparticles supported by functionalized carbon nanotubes (CNTs) were prepared for the first time. Nickel (II) dihydrogenphosphite as a source of nickel, with different loadings on the functionalized CNTs, were used. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) techniques. Surface areas of the samples were measured by using Brunauer, Emmett and Teller (BET) method. The catalytic activity of the prepared samples was studied in hydrodesulfurization (HDS) of naphtha. The results showed that the CNTs were

functionalized and Ni₂P particles were dispersed on the functionalized CNTs. It was also indicated that the pores size of Ni₂P particles were less than 20 nm. The catalytic study of the prepared samples confirmed that these compounds were stable and active in the process. Removal of sulfur from the desired naphtha in presence of the samples depended on the nickel loadings and increased with temperature in all cases.     

A Supramolecular Star-like Tungstoarsenate(V) with Uranyl Cations: [(NH4)12(UO2(H2O))6(UO2(μ2-H2O))6(α-AsW9O34)6]18?

A supramolecular tungstoarsenate(V) containing UO₂ ²⁺ cations has been isolated by reaction of the ammonium salt of lacunary sandwich-type anion [As₂W₁₈(UO₂)₂O₆₈]¹⁴⁻ in aqueous solution of Ce^IV (pH 3.5). The product prepared as NH₄ ⁺ salt, (NH₄)₁₈[(NH₄)₁₂(UO₂(H₂O))₆(UO₂(μ₂-H₂O)₆(α-AsW₉O₃₄)₆]·74H₂O (I), have been characterized by single crystal X-ray diffraction, elemental analysis, IR, and UV/vis spectroscopy. The anion consists on six lacunary α-AsW₉O₃₄ ⁹⁻ anions linked by twelve UO₂ ²⁺ cations which resembles a star (six-member). The single crystal structure of I reveals two types uranium atoms; six uranium atoms in the central of anion form two U₃O₃ trigonal bridging groups in which each uranium atom bounds to three oxygen atoms of one AsW₉ and two bridging water ligands. The other uranium atoms form two equatorial bonds to one AsW₉ and two equatorial bonds to two other AsW₉ fragments. The UV/vis spectroscopy confirms the strong coordination of oxygen atoms of α-AsW₉O₃₄ ⁹⁻ anions to uranyl cations in the equatorial plane.     

Monophosphoramide derivatives: synthesis and crystal structure,theoretical and experimental studies of their biological effects

Molecular Diversity - Synthesizing new chemical compounds and studying their biological applications have been important issues in scientific research. In this investigation, we synthesized and...     

Optimization of One-Way Quantum Computation Measurement Patterns

In one-way quantum computation (1WQC), an initial highly entangled state, called a graph state, is used to perform universal quantum computations by a sequence of adaptive single-qubit measurements and post-measurement Pauli-X and Pauli-Z corrections. 1WQC computation can be represented by a measurement pattern (or simply a pattern). The entanglement operations in a pattern can be shown by a graph which together with the identified set of its input and output qubits is called the geometry of the pattern. Since a pattern is based on quantum measurements, which are fundamentally nondeterministic evolutions, there must be conditions over geometries to guarantee determinism. These conditions are formalized by the notions of flow and generalized flow (gflow). Previously, three optimization methods have been proposed to optimize 1WQC patterns which can be performed using the measurement calculus formalism by rewriting rules. However, the serial implementation of these rules is time consuming due to executing many ineffective commutation rules. To overcome this problem, in this paper, a new scheme is proposed to perform the optimization techniques simultaneously on patterns with flow and only gflow based on their geometries. Furthermore, the proposed scheme obtains the maximally delayed gflow order for geometries with flow. It is shown that the time complexity of the proposed approach is improved over the previous ones.