海蛎壳粉废弃物负载CuCl_2作为高效、廉价以及可回收催化剂合成炔胺类化合物(英文)

发展了一种经济、简单的海蛎壳粉负载的CuCl2异相催化剂OSP-CuCl2,用来催化醛-炔-胺之间的A3偶联反应.OSP-CuCl2容易通过简单的方法从海蛎壳粉以及CuCl2制备,且显示出高的催化活性以及良好的可循环回收性.在微波辅助以及无溶剂条件下,以OSP-CuCl2为催化剂,能够以高产物收率制备出一系列炔胺类化合物.OSP-CuCl2可通过简单的过滤方式进行回收,并至少可循环使用6次.初步放大实验表明,炔胺类化合物能够以150 mmol的规模制备(87%收率).     

In situ phosphorus K-edge X-ray absorption spectroscopy studies of calcium–phosphate formation and transformation on the surface of bacterial cellulose nanofibers

In this work, for the first time, in situ formation and transformation process of embryo calcium phosphate (Ca–P) minerals on three-dimensional bacterial cellulose nanofibers was investigated. Combined with XRD, X-ray absorption near-edge structure results revealed that the embryo precursor was amorphous calcium phosphate which was subsequently converted to β-tricalcium phosphate, octacalcium phosphate, and finally to the more thermodynamically stable form of hydroxyapatite. The methodology reported herein may be extended to the studies of Ca–P and other minerals on various substrates.     

A Network Model for Diffusion in Media with Partially Resolvable Pore Space Characteristics

A microstructure-informed meso-scale model for diffusion of foreign species in porous media is proposed. The model is intended for media where the pore geometry data acquired experimentally represent a fraction of total porosity. A cellular complex, with a cell representing the average pore neighbourhood, is used to generate 3D graphs of sites at cell centres and bonds between neighbouring cells. The novel interpretation of pore systems as graphs allows for clear separation between topology (here connectedness) and physics (here diffusion) in the mathematical formulation of transport. Further, it allows for easy introduction of dynamics into the system, i.e., local changes in topology due to other physical mechanisms, such as micro-cracking or blockage of pores. A mapping between microstructure features and graph elements is used for model construction. The mapping is based on data for clays, where the experimentally resolved pore system comprises isolated elongated pores of preferred orientation with a large volume fraction of unresolved pores. Both the resolved and the “hidden” systems are accounted for. The graph geometry is described by a principal length, the cell size in the preferred orientation, and a secondary length, the cell size out of preferred orientation. This is considered as a representation of mineralogical heterogeneity of clays. Analysis on graphs, a specialisation of the discrete exterior calculus, is used to obtain connectivity and diffusivity properties of formed networks. Since the experimental data are not sufficient to determine the principal length, upper and lower limits are determined from the limited information. Effects of the principal cell size between limits and of the secondary cell size are studied. The results are within the range of experimentally measured macroscopic (bulk) diffusivity for the material studied, including anisotropic diffusion coefficients. The variation of calculated diffusivity coefficients with principal and secondary lengths provides an explanation for the variability in experimentally measured coefficients across different clays.     

Total Synthesis of Hapalindole‐Type Natural Products

A unified and bioinspired oxidative cyclization strategy was used in the first total syntheses of naturally occurring 12‐epi‐hapalindole Q isonitrile, hapalonamide H, deschloro 12‐epi‐fischerindole I nitrile, and deschloro 12‐epi‐fischerindole W nitrile, as well as the structural revision of the latter. Hapalindoles H and Q were also synthesized.     

Ni基催化剂上的乙烷部分氧化制合成气

There is abundant supply of light alkanes and relatively few routes of converting them to more valuable products. Although CH4 predominates in natural gas, it also contains C2H6, C3H8 and C4H10 (from 5 % to 30% ), and with C2H6 as the most abundant secondary component[1]. Partial oxidation of methane to syngas (CH4 +0.5O2 →CO + 2H2) over nickel-based catalysts has received intensive attention[2]and much research has been devoted to conversion of ethane to ethylene[3]. Ethylene has been shown to be formed from ethane by thermal dehydrogenation (C2H6 →C2H4 + H2) and oxidative dehydrogenation (C2H6 + 0. 5O2 →C2H4 + H2O). These processes are operated under severely fuel-rich conditions. The carbon-deposition and consequent deactivation of the catalysts are major problems, which leads to poor conversion of the above mentioned reactions. As an alternative strategy for the elaboration of ethane, little work on the partial oxidation of ethane (POE) to syngas over nickel-based catalysts has been reported. Provided it could be produced from C2H6with high selectivity and high conversion over nickel-based catalysts, syngas could be directly obtained from natural gas including CH4 and C2H6 with high selectivity and conversion. This may lead to better utilization of the light fractions from natural gas and refineries. In the present paper, POE to syngas over nickel-based catalysts was investigated.     

Catalytic carbon dioxide hydrogenation to methane: A review of recent studies

Recently,various efforts have been put forward on the development of technologies for the synthesis of methane from CO₂ and H₂,since it can offer a solution for renewable H₂ storage and transportation.In parallel,this reaction is considered to be a critical step in reclaiming oxygen within a closed cycle.Over the years,extensive fundamental research works on CO₂ methanation have been investigated and reported in the literatures.In this updated review,we present a comprehensive overview of recent publications during the last 3 years.Various aspects on this reaction system are described in detail,such as thermodynamic considerations,catalyst innovations,the influence of reaction conditions,overall catalytic performance,and reaction mechanism.Finally,the future development of CO₂ methanation is discussed.     

Fluoroalkylation of poly(cyclopentadienyl)siloxane and the surface properties of poly(fluorocyclopentenyl)siloxane films

In this work, poly(fluorocyclopentenyl)siloxane (FPCS) was obtained via a single electron transfer addition reaction of poly(cyclopentadienyl)siloxane (PCS) and perfluoroalkyl iodides, and reduction reaction of the intermediates. PCS was prepared by substitution and hydrolysis reactions using methyltrichlorosilane and sodium cyclopentadienide (NaCp) as raw materials. Fourier transform infrared (FTIR), ¹H NMR, and ¹⁹F NMR indicated the structures of the target polymers. The XPS results showed that the thin films prepared by dip-coating were fluorine enriched at the surface. Atomic force microscopy (AFM) image showed that on the rough surface of films, there were many pinnacles which were generated through the migration of side chain fluoroalkyl groups. The relative static contact angles of water and n-hexadecane on FPCS and PCS indicated that sodium dithionite initiated the reaction of perfluoroalkyl iodides and PCS so that FPCS was successfully synthesized. The measured surface energy of PCS was 2.57 × 10^?2 N/m; while FPCS was 2.14 × 10^?2 N/m, which represented better liquid repellent property compared to PCS.     

Development and validation of an LC/MS/MS method for simultaneous determination of shionone and epi‐friedelinol in rat plasma for pharmacokinetic study after oral administration of Aster tataricus extract

A rapid and sensitive liquid chromatography tandem mass spectrometry (LC/MS/MS) method was developed and validated using spinasterol as the internal standard (IS) for the simultaneous determination of shionone and epi‐friedelinol in rat plasma. Plasma samples were pretreated using liquid–liquid extraction with ethyl ether. Chromatographic separation was achieved on a C₁₈ column (100 × 2.1 mm, 5 μm) with an isocratic elution consisting of acetonitrile–0.1% formic acid water (75:25, v/v) at a flow rate of 0.30 mL/min. Detection was performed under the selected reaction monitoring scan using an electrospray ionization in the positive ion mode. The mass transitions were as follows: m/z 427.4 → 95.1 for shionone, m/z 411.4 → 205.2 for epi‐friedelinol and m/z 395.3 → 105.2 for IS. All calibration curves exhibited good linearity (r > 0.995) over the concentration range for both components. The intra‐ and inter‐day precisions at three QC and lower limit of quantitation levels were both <10.21% in terms of relative standard deviation, and the accuracy ranged from ?7.13 to 8.02% in terms of relative error. The extraction recoveries of the compounds ranged from 82.07 to 89.81%. The developed method was successfully applied to the pharmacokinetic study of shionone and epi‐friedelinol after oral administration of Aster tataricus extract to rats. Copyright © 2015 John Wiley & Sons, Ltd.     

A Pronounced Halogen Effect on the Organogelation Properties of Peripherally Halogen Functionalized Poly(benzyl ether) Dendrons

An interesting halogen‐substituent effect on the organogelation properties of poly(benzyl ether) dendrons is reported. A new class of poly(benzyl ether) dendrons with halo substituents decorating their periphery was synthesized and fully characterized. A systematic study on the gelation abilities, thermotropic behaviors, aggregated microstructures, and mechanical properties of self‐assembled organogels was performed to elucidate the halogen‐substituent effects on their organogelation propensity. It was found that the exact halogen substitutions on the periphery of dendrons exert a profound effect on the organogelation propensity, and dendrons G _n ‐Cl (n=2, 3) and G₂‐I proved to be highly efficient organogelators. The cooperation of multiple π–π, dispersive halogen, CH–π, and weak C?H ??? X hydrogen‐bonding interactions were found to be the key contributor to forming the self‐assembled gels. Dendritic organogels formed from G _n ‐Cl (n=2, 3) in 1,2‐dichloroethane exhibited thixotropic‐responsive properties, and such thixotropic organogels are promising materials for future research and applications.