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61.
Cyclic α-trimethylsilylketones are synthesized from cyclic vinyltrimethylsilanes via the epoxides , and the alcohols . 相似文献
62.
Formation of CoAl3Cl11 at higher Al2Cl6 Pressures The reaction of CoCl2,f with Al2Cl6,g (≈ 3 atm) is investigated considering every component of the gas phase (Al2Cl6, AlCl3, Al3Cl9, CoAlCl5, CoAl2Cl8, CoAl3Cl11) and the deviation from the ideal behaviour. The conclusion is derived that at 600 K from CoCl2,s and larger pressures of Al2Cl6 besides CoAl2Cl8 a small amount of CoAl3Cl11 is formed. 相似文献
63.
Kai Li Harald D. H. Stver 《Journal of polymer science. Part A, Polymer chemistry》1993,31(10):2473-2479
Narrow disperse microparticles are formed by dispersion polymerization of commercial divinylbenzene in acetonitrile or ethanol solution in the presence of 2,2′-azobis(2-methylpropionitrile) initiator and polyvinylpyrrolidone stabilizer. The particles have average diameters between 1 and 9 μm depending on monomer concentration, solvent, and temperature. While the smaller particles are relatively smooth, surface texture increases with diameter to give popcorn shapes at 9 μm diameter. High crosslinker concentration is shown to be essential for particle formation. © 1993 John Wiley & Sons, Inc. 相似文献
64.
The fluorescence peak of isoquinoline increases strongly in intensity with increasing pressure in polymethylmethacrylate (PMMA) and in polyisobutylene (PIB). In polyvinylalcohol the intensity decreases as the pressure increases. In all three cases the emission peak shifts to lower energy as the pressure increases. The results are consistent with the hypothesis that the ππ* state lies higher in energy than the nπ* state in non-hydrogen bonding solvents, but that the situation is reversed in hydrogen bonding solvents. 相似文献
65.
Ernst Berger David W. T. Griffith Gerhard Schuster Stephen R. Wilson 《Mikrochimica acta》1988,95(1-6):239-241
The use of an integrating sphere for the measurement of absorption spectra of thin films is described. The thin film (for example a rare gas matrix) is grown directly on the inside surface of the sphere. Multiple reflections inside the integrating sphere lead to significant enhancement of weak absorptions of the film, increasing the sensitivity of such measurements. 相似文献
66.
Potential curves for proton transfer in [H5O2]+ and for the dissociation of one OH bond in [H3O]+ were calculated by both ab initio and semi-empirical LCAO MO SCF CI methods. The energy barrier of the symmetric double minimum potential in [H5O2]+ is very sensitive to electron correlation. At an OO distance of 2.74 Å it decreases from the HF value of 9.5 kcal/mole to about 7.0 kcal/mole. The results of the semi-empirical calculations agree well with the ab initio data as long as only relative effects are regarded. The partitioning of correlation energy into contributions of individual electron pairs is very similar for proton transfer in [H5O2]+ and for the dissociation of one OH bond in [H3O]+. In this example the proton transfer appears as a superposition of two “contracted ionic dissociation” processes. An interpretation of the behaviour of correlation during these processes is presented. 相似文献
67.
Ab initio calculations on formaldehyde/Li+ complexes are presented. The most stable arrangement is characterized by an energy of interaction of 43.2 kcal/mole, C2v symmetry and an oxygen—lithium distance of ROLi = 1.77 Å. A detailed analysis of the electron density function gives proof of the electrostatic nature of the complexes H2O/Li+ and H2Co/Li+ and shows extensive mutual polarization. The failure of the semi-empirical method to predict the changes in electron density at the Li+ cation correctly is explained. 相似文献
68.
Gaseous Acetates Thermoanalytical and mass-spectrometrical observations are undertaken with some acetates and oxiacetates. The volatilization of copper(I) acetate takes place like that of the silver acetate as M2Ac2+ (besides the deposition of Ag). On the volatilization of the anhydrous compounds Cu2Ac4, Cr2Ac4, Rh2Ac4, and Mo2Ac4 in the vacuum of a mass spectrometer is observed that Cu2Ac4 vaporizes dissociative as Cu2Ac2+ (+ 2 “Ac”), while the other compounds vaporize as M2Ac4+ and simultaneously is formed an oxidic (e.g. Cr2O4) or metallic residue. PdAc2 vaporizes in the mass spectrometer as a trimeric molecule Pd3Ac6. M4OAc6, which is formed from the dihydrates, vaporizes in a mass spectrometer with M ? Co, Mn as M4OAc6+. Other complexes of the same type appear as Be4OAc5+, Mg4OAc5+, and Zn4OAc5+. 相似文献
69.
New Ternary Clathrate Compounds in the Systems Barium–Indium/Zinc/Cadmium–Germanium: Zintl Compounds with Phase Width? By systematic investigations in the systems barium–indium/zinc/cadmium–germanium we found a couple of new electrovalent ternary compounds with A8X46 clathrate (I) type structures. They crystallize cubically in space-group Pm3n. For Ba8In16Ge30 (a = 1 075.8 pm), Ba8Zn8Ge38 (a = 1 082.0 pm) and Ba8Cd8Ge38 (a = 1 096.0 pm) the structures were verified by X-ray single crystal diffraction data. According to valence and bounding distances the new clathrates should be Zintl compounds. Measurements of the temperature dependence of the electrical resistivity proved, that they are indeed semiconductors. A part of the 2B/3B metal atoms can be substituted by germanium. Charge balance will be retained by creation of vacancies in the A8X46 type structures. By phase analysis the limits of the composition range were determined as Ba8In4Ge9[]3Ge30 (a = 1 084.9 pm), Ba8Zn4Ge10[]2Ge30 (a = 1 073.6 pm) and Ba8Cd4Ge10[]2Ge30 (a = 1 082.0 pm). 相似文献
70.
Harald Greger Otmar Hofer Andreas Werner 《Monatshefte für Chemie / Chemical Monthly》1985,116(2):273-277
In addition to the well known affinin [=spilanthol, (2E,6Z,8E)-deca-2,6,8-trienoic acid isobutylamide (1)], the corresponding 2-methyl-butylamide (2), and two new acetylenic alkamides were isolated fromSpilanthes oleracea L. by reversed phase medium pressure chromatography: (Z)-non-2-en-6,8-diynoic acid isobutylamide (3) and (Z)-dec-2-en-6,8-diynoic acid isobutylamide (4). The structures and their stereochemistries were elucidated by1H-NMR,13C-NMR (2 and3), MS, UV, IR, and CD (2). The chemotaxonomic significance of the distribution of alkamides within theCompositae tribeHeliantheae is briefly discussed.
Neue Amide ausSpilanthes oleracea (Kurze Mitteilung)
Zusammenfassung AusSpilanthes oleracea wurden neben dem seit langem bekannten Affinin [=Spilanthol, (2E,6Z,8E)-Deca-2,6,8-triensäureisobutylamid (1)] durch Umkehrphasen-Mitteldruckchromatographie das entsprechende 2-Methylbutylamid (2) und zwei neue acetylenische Alkamide isoliert: (Z)-Non-2-en-6,8-diinsäure-isobutylamid (3) und (Z)-Dec-2-en-6,8-diinsäure-isobutylamid (4). Die Strukturen und deren Stereochemie wurden mittels1H-NMR,13C-NMR (2 und3), MS, UV, IR und CD (2) aufgeklärt. Die chemotaxonomische Bedeutung der Verbreitung von Alkamiden innerhalb der Compositen-TribusHeliantheae wird kurz diskutiert.相似文献