1,7-Enynes 1, connected through an aromatic ring and bearing a leaving methoxy group at the 4-position, underwent the PtBr(2)-catalyzed enyne metathesis followed by aromatization in one pot to afford vinyl naphthalenes 3 in good to acceptable yields. The cyclobutene intermediate 11a and another intermediate 2a were isolated, indicating that PtBr(2) acts as a dual role catalyst: (1) as a transition metal catalyst, it induces the enyne metathesis to produce 11a starting from 1a, and (2) as a Lewis acid catalyst, it facilitates elimination of MeOH from 2a to give the aromatized product 3a. 相似文献
The new mixed-valence mixed-metal complex Cu(py)6Cu2Ag2(CN)6 (py = pyridine) possesses a three dimensional polymeric crystal structure. The Cu(I) atom is tetrahedrally coordinated by
two nitrogen atoms of pyridine molecules, by one nitrogen atom of the dicyanoargentate anion and by one carbon atom of the
cyano group. Both the dicyanoargentate anion and the cyano group bridge the Cu(I) atom with neighboring Cu(II) atoms. These
are hexacoordinated in the form of an elongated tetragonal bipyramid. The equatorial plane is formed by two nitrogen atoms
from two pyridine molecules and two nitrogen atoms from bridging cyano groups. Axial positions are occupied by nitrogen atoms
of the bridging [Ag(CN2]− anions. Correlation between structures of the title compound and seven other dicyanoargentates with their i.r. spectra has
been studied. The coordination mode of [Ag(CN2]− anions in compounds Cu8-xAgx(tn)3(CN)10x = 0.25, Cu(3-Mepy)2Ag2(CN)4, Cu(py)2Ag2(CN)4 and Cu(py)4Ag2(CN)4 (tn is 1,3-diaminopropane, 3-Mepy is 3-methylpyridine) is predicted based on this correlation. 相似文献
Summary Copper has been determined gravimetrically as its bis-salicylaldehyde-ethylenediamine complex of the composition C16H14O2N2 · Cu, dried at 100–120° C. The complex is completely precipitated in theph range of 10.5–13.5, adjusted with ammonia or caustic alkali. It is stable in presence of excess ammonia, 0.1 N alkali, ammonium salts and complexing agents as tartrate, citrate, sodium-thiosulphate, fluoride, thiourea, triethanolamine and EDTA. In presence of tartrate and ammonia the ions of alkali metals, alkaline earths, Ag+, Tl+, Tl3+, Pb2+, Cd2+, Co2+, Mn2+, Pd2+, Al3+, Cr3+, La3+, Ce3+, Au3+, Pt4+, Ti4+, Zr4+, Th4+, UO22+ and anions as VO3–, MoO42–, WO42–, CrO42–, PO43–, AsO43– do not interfere. Ni2+ and Hg2+ are masked by tartrate, EDTA and ammonia; As3+, Sb3+ and Sn2+ are separated using fluoride as the complexing agent; at an alkalinity of 0.1 N caustic alkali in presence of tartrate As3+, Sb3+, Sn2+, Bi3+, Zn2+ and Fe3+ are separated. Fe3+ can also be separated using triethanolamine as the masking agent at aph of about 13.0. Copper can be separated from almost all the ions, thus affording a highly selective method for the determination of copper.
Zusammenfassung Es wird eine gravimetrische Methode zur Bestimmung von Kupfer beschrieben, die auf der Bildung des Bis-salicylaldehyd-äthylendiaminkomplexes beruht. Dieser hat die Zusammensetzung C16H14O2N2 · Cu. Die Fällung wird imph-Bereich 10,5–13,5 (mit Ammoniak oder Alkalilauge eingestellt) vorgenommen und der Niederschlag bei 100°–120° C getrocknet. Der Komplex ist beständig in Gegenwart von überschüssigem Ammoniak, 0,1 n Alkali, Ammoniumsalzen sowie Tartrat, Citrat, Natriumthiosulfat, Fluorid, Thioharnstoff, Triäthanolamin und ÄDTA. In Gegenwart von Tartrat und Ammoniak stören nicht: Alkalien, Erdalkalien, Ag+, Tl+, Tl3+, Pb2+, Cd2+, Co2+, Mn2+, Pd2+, Al3+, Cr3+, La3+, Ce3+, Au3+, Pt4+, Ti4+, Zr4+, Th4+, UO22+ sowie VO3–, MoO42–, WO42–, CrO42–, PO43– und AsO43+. Ni2+ und Hg2+ können mit Tartrat, ÄDTA und Ammoniak maskiert werden, As3+, Sb3+ und Sn2+ mit Fluorid. In 0,1 n ätzalkalischer Lösung in Gegenwart von Tartrat können As3+, Sb3+, Sn2+, Bi3+, Zn2+ und Fe3+ abgetrennt werden. Fe3+ kann ebenfalls mit Triäthanolamin beiph 13,0 maskiert werden. Das beschriebene Verfahren erlaubt somit eine Abtrennung des Kupfers von fast allen anderen Ionen.
Part I: Singh, B. R., and S. Kumar: Z. analyt. Chem. 185, 211 (1962). 相似文献
Abstract We present here precise measurements of the layer spacing for two compounds, viz. 4-n-heptyloxyphenyl-4′-(4″-cyanobenzoyloxy)benzoate and 4-n-undecyloxyphenyl-4′-(4″-cyanobenzyloxy)benzoate. Contrary to earlier reports our data do not show any jump in the layer spacing at the expected Ad-A2 transition temperature, showing thereby that for both compounds A2 evolves continuously from the Ad phase. 相似文献
In this report we demonstrate the ability to tune the physical properties of a liquid crystal elastomer (LCE) by varying the amount and type of crosslinking within the elastomer network. LCE films composed of a single mesogenic compound were capable of uniaxial contraction when thermally actuated through the nematic to isotropic phase of the material. We probed the physical properties of the LCE films while varying the amount and concentration of two crosslinking agents and measured actuation strains of 10–35%, elastic moduli of 3–14 MPa, and transition temperatures ranging between 75 and 60°C. The viscous losses of the elastomers and the estimated work capable of being produced by the films were also evaluated. The ability to tune the physical properties of the LCE films allows for a wide range of applications including robotics, microelectromechanical systems (MEMS), shape‐changing membranes, and/or microfluidics. 相似文献
Hydroxyapatite-supported Ni-Ce-Cu catalysts were synthesised and tested to study their potential for use in the steam reforming of glycerol to produce hydrogen. The catalysts were prepared by the deposition-precipitation method with variable nickel, cerium, and copper loadings. The performance of the catalysts was evaluated in terms of hydrogen yield at 600°C in a tubular fixed-bed microreactor. All catalysts were characterised by the BET surface area, XRD, TPR, TEM, and FE-SEM techniques. The reaction time was 240 min in a fixed-bed reactor at 600°C and atmospheric pressure with a water-to-glycerol feed molar ratio of 8: 1. It was found that the Ni-Ce-Cu (3 mass %-7.5 mass %-7.5 mass %) hydroxyapatite-supported catalyst afforded the highest hydrogen yield (57.5 %), with a glycerol conversion rate of 97.3 %. The results indicate that Ni/Ce/Cu/hydroxyapatite has great potential as a catalyst for hydrogen production by steam reforming of glycerol. 相似文献
Electricity generation using simple and cheap dye-sensitized solar cells and photocatalytic water splitting to produce future fuel, hydrogen, directly under natural sunlight fascinated the researchers worldwide. Herein, synthesis of indium-doped wurtzite ZnO nanostructures with varying molar percentage of indium from 0.25 to 3.0% with concomitant characterization indicating wurtzite structure is reported. The shift of (002) reflection plane to higher 2θ degree with increase in indium-doping thus is a clear evidence of doping of indium in zinc oxide nanoparticles. Surface morphological as well as microstructural studies of In@ZnO exhibited generation of ZnO nanoparticles and nanoplates of diameter 10–30 nm. The structures have been correlated well using computational density functional (DFT) studies. Diffuse reflectance spectroscopy depicted the extended absorbance of these materials in the visible region. Hence, the photocatalytic activity towards hydrogen generation from water under natural sunlight as well as efficient DSSC fabrication of these newly synthesized materials has been demonstrated. In-doped ZnO exhibited enhanced photocatalytic activity towards hydrogen evolution (2465 μmol/h/g) via water splitting under natural sunlight. DSSC fabricated using 2% In-doped ZnO exhibited an efficiency of 3.46% which is higher than other reported In-doped ZnO based DSSCs.
Solubility of several anthraquinone derivatives in supercritical carbon dioxide was readily available in the literature, but correcting ability of the existing models was poor. Therefore, in this work, two new models have been developed for better correlation based on solid–liquid phase equilibria. The new model has five adjustable parameters correlating the solubility isotherms as a function of temperature. The accuracy of the proposed models was evaluated by correlating 25 binary systems. The proposed models observed provide the best overall correlations. The overall deviation between the experimental and the correlated results was less than 11.46% in averaged absolute relative deviation (AARD). Moreover, exiting solubility models were also evaluated for all the compounds for the comparison purpose. 相似文献
Density functional theory and multiconfigurational CASPT2 and density matrix renormalization group DMRG-CASPT2 have been employed to study the low-lying states of NbGen−/0/+ (n = 1–3) clusters. With the DMRG-CASPT2 method, the active spaces are extended to a size of 20 orbitals. For most of the states, the CASPT2 relative energies are comparable with the DMRG-CASPT2 results. The leading configuration, bond distances, vibrational frequencies, and relative energies of the low-lying states of these clusters were calculated. The ground states of these clusters were computed to be 3Δ, 4Φ, and 5Φ of NbGe−/0/+; 3A2, 4B1, and 3B1 of cyclic-NbGe2−/0/+; and 1A′, 12A″ and 12A′′ (2E), and 3A″ of tetrahedral-NbGe3−/0/+ isomers. For NbGe cluster, our calculations proposed that the 6∑ is almost degenerate with the 4Φ with the CASPT2 and DMRG-CASPT2 relative energies of 0.05 and 0.06 eV. The adiabatic detachment energies of NbGen− (n = 1–3) clusters were estimated to be 1.46, 1.55, and 2.18 eV by the CASPT2 method. The relevant detachment energies of the anionic ground state and the ionization energies of the neutral ground states are evaluated at the CASPT2 level. 相似文献