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991.
Qing Qing Meng He Xiang Bai Feng Li Quan Rui Wang Feng Gang Tao 《中国化学快报》2007,18(7):785-787
A convenient synthetic pathway to 2-aryl-5,6-dihydro-4H-benzo[f][1,2,4]triazolo[1,5-α]azepine derivatives 7 was developed. The synthesis was based on the cycloaddition of the 1,2,3,4-tetrahydronaphthalene a-acetoxy azo compounds 3 with Ar-CN in the presence of AlCl3 and the consecutive ring enlargement. 相似文献
992.
The goal of this work was the development of a novel type of heterogeneous catalyst, consisting of bare metal nanoparticles
on stainless steel foils, which can be shaped to any kind of architecture and, if necessary, heated electrically. Solutions
of pre-prepared, ligand protected and monodispersed gold, palladium, platinum and rhodium nanoparticles were sprayed onto
stainless steel foils, followed by the careful removal of the ligand molecules by an oxygen plasma treatment. Due to this,
bare particles become irreversibly fixed on the steel support. It could be shown that the original particle sizes do not change
during the plasma treatment. Foils, densely coated with the nanoparticles, were used for gas phase catalyses in a self-made
reactor at room temperature or at 60 °C. Hydrogenation of 1,3-butadiene at 15 nm Pd and 2 nm Pt, CO oxidation at 16 nm, 8 nm
and 1.4 nm gold and NO reduction with NH3 at 2 nm Rh particles were performed, indicating that the novel catalysts might in principle be applicable in technical processes
if the experimental conditions like form and temperature would be optimized.
Dedicated to Professor Dieter Fenske on the occassion of his 65th birthday. 相似文献
993.
Xiao-Bai Sun Pei-Hua Zhao Yang-Jun Xu Li-Mei Sun Mei-Ai Cao Cheng-Shan Yuan 《Chemistry of Natural Compounds》2007,43(5):563-566
Investigation of the roots of Polygonum bistorta L. afforded seven compounds including five triterpenoids, a coumarin, and a steroid, the structures of which were identified
by EIMS, 1H NMR, 13C NMR, DEPT, and HMBC experiments. All the compounds have been isolated from Polygonum genus for the first time.
Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 463–465, September–October, 2007. 相似文献
994.
A new Schiff base has been synthesized from 4-aminoantipyrine and 3-formylsalicylic acid. The ligand has a dianionic tetradentate compartmental OONO donor system. The cobalt(II), nickel(II), copper(II) and dioxouranium(VI) complexes exist in phenolato-bridged dinuclear species, while palladium(II) gives a mononuclear complex with free –COOH groups. The complexes have been characterized by elemental analyses, i.r., u.v.-vis, thermal and magnetic measurements. 相似文献
995.
Wanxing Wei Yuanjiang Pan Yaozu Chen Cuiwu Lin Tengyou Wei Shukai Zhao 《Chemistry of Natural Compounds》2005,41(1):17-21
Five compounds, terephthalic acid mono-[2-(4-carboxy-phenoxycarbonyl)-vinyl] ester (1), (E)-3-(5′-hydroperoxy-2,2′-dihydroxy[1,1′-biphenyl]-4-yl)-2-propenoic acid (2), 3,4,5-trihydroxybenzoic acid (3), succinic acid (or butanedioic acid) (4), and 2,3,4,5,6-pentahydroxybenzoic acid (5), were isolated from Phyllanthus urinaria. The structures of these compounds were elucidated by means of spectral techniques including IR, MS, and 1D/2D NMR. 1 and 2 are new compounds.__________Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 14–17, January–February, 2005. 相似文献
996.
Mariko Kusabe Hiromitsu Kozuka Satoru Abe Hiroshi Suzuki 《Journal of Sol-Gel Science and Technology》2007,44(2):111-118
Hydroxypropylcellulose (HPC)–titania hybrid thin films were prepared by sol–gel method where titanium tetraisopropoxide Ti(OC3H7
i
)4 was hydrolyzed under acidic conditions in the presence of HPC, followed by dip-coating and drying at 120 °C for 24 h. The
viscosity average molecular weight of HPC was 55,000–70,000 or 110,000–150,000, and the TiO2/(HPC + TiO2) mass ratio ranged from 0 to 1, which was calculated on the assumption that all Ti(OC3H7
i
)4 is converted into TiO2. The films were 0.35–1.0 μm thick, transparent in visible region and opaque in ultraviolet (UV) region, where the optical
absorption coefficient in UV region increased with increasing titania content. The refractive index increased with increasing
titania content, ranging from 1.6 to 1.8 for the hybrid thin films. The pencil hardness increased from 6B to 5H, the durability
in hot water significantly increased and the contact angle of water on films increased from 35° to 89° with increasing titania
content. Crack-free films could be deposited on organic polymer substrates irrespective of titania or HPC contents, where
cracking did not occur at higher HPC contents even when the substrate was bent. 相似文献
997.
Electron impact mass spectra of eight of the title compounds are reported. Abundant fragment ions were produced under electron impact (EI) conditions and, with one exception, the ($?hbox?ArC??equiv$ O) ions were the base peaks. The EI fragmentation mechanisms of two representative compounds were studied with the aid of high-resolution and mass-analyzed ion kinetic energy spectrometry (MIKES) data. The M(+) ions fragment to give both an odd-electron ion and an even-electron fragment ion. Two H-atom rearrangements proceeding via four-membered ring intermediates and three losses of CO through i- and alpha-fragmentations were observed under EI. On comparing fragmentations under EI conditions with those under FAB conditions for two of the compounds, the fragmentation mechanisms were reasonably similar, with additional fragmentations rationalized in terms of the ionization proton being located on the oxygen atom of the beta-ethoxy group. 相似文献
998.
Q. Zhong L. He T. E. Beesley W. S. Trahanovsky P. Sun C. Wang D. W. Armstrong 《Chromatographia》2006,64(3-4):147-155
The comparisons of five different chiral stationary phases (CSPs) based on 2,6-dinitro-4-trifluoromethylphenyl (DNP-TFM) ether substituted β-cyclodextrin are presented. The five CSPs differ from each other in the linkage/spacer chemistry, or on the position of the substituents on β-cyclodextrin, or in the sequence of the synthetic procedure. The results show that there are two optimum combinations: (1) DNP-TFM randomly substituted on the β-cyclodextrin as the chiral selector along with a carbamate linkage chain bonding it to the silica support; and (2) β-cyclodextrin derivatized by DNP-TFM substituents only on the C-2 and C-3 positions of the cyclodextrin with an ether linkage chain anchoring it to the silica gel. These two combinations show complementary separations for some enantiomers. The spacer chain effect is much more pronounced for the CSP based on the β-cyclodextrin derivatives with DNP-TFM substituents only on C-2 and C-3 positions than its randomly substituted counterpart. The sequence of derivatizing the cyclodextrin and attaching it to silica gel also affects its selectivity and efficiency. The β-cyclodextrin should be derivatized before it is linked to the silica gel. 相似文献
999.
The stability of spontaneous thin layers and thin layers formed upon cathodical polarization of Ti in KOH solutions have been
studied by potentiostatic and ellipsometric methods. At open circuit potential (OCP) the strongly adherent films, whose thickness
depends on the concentration of the KOH solution, were formed. During the cathodic polarization the transformation of these
films to weakly adsorbed precipitated layers on the electrode surface was observed. Comparing the theoretically computed curves
with the experimental Ψ vs Δ loci measured ellipsometrically, the complex indices of refraction and the thickness of the generated films, from 3.6
to 60 nm in 1 M KOH and from 36 to 105 nm in 5 M KOH (adherent to the electrode surface), were determined. At OCP the rate
of film growth increases with increasing the concentration of KOH solution. Cathodic polarizations change the chemical composition
and retard the rate of film growth. Based on the ellipsometric and electrochemical data the chemical compositions of the formed
films consisted of TiO2, Ti2O3, TiO2·H2O, Ti(OH)3 and TiOOH·nH2O. 相似文献
1000.
Xiufang Xu Guichang Wang Xuezhuang Zhao Yinming Pan Yunxiao Liang Zhenfeng Shang 《Journal of mathematical chemistry》2007,41(2):143-160
In this paper, the fuzzy symmetry of some prototypical linear molecules has been analyzed. The results show that some molecular
orbitals (MOs) are less symmetrical but some others are more symmetrical than the molecular skeleton, which the MOs correspond
to. The membership functions of space inversion for MOs are closely related to the chemical characteristics of the MOs. Sometimes,
although the symmetry of a molecular skeleton is not obvious, however that of some MO is quite obvious. The membership functions
of the fuzzy inversion symmetry depend on the choice of the position of the center of inversion. As compared to those of diatomic
molecules and linear tri-atomic molecules, the linear polyatomic molecules in which a distinctive fuzzy symmetry of space
translation may exist, and thus a significant effect on their properties can be expected. 相似文献