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31.
Gerhard Buchbauer Johanna Gabmeier Ernst Haslinger Wolfgang Robien Harald Steindl 《Helvetica chimica acta》1985,68(1):231-235
Synthesis and Reactions of the Bicyclo[6.4.0]dodecane-3-carboxylic Acid Derivatives The synthesis and some consecutive reactions of the compounds 5-8 , derivatives of bicyclo[6.4.0]dodecane-3-carboxylic acid ( 1 ), are described. The esters 7 and 8 can be obtained by Baeyer-Villiger oxidation of 2-hydroxy-8-methyltricyclo[7.3.1.02,7]tridecan-13-one ( 4 ) and subsequent hydrolysis of the lactone 5 . The structure and configuration of these compounds has been evaluated by spectroscopic techniques (mainly 2D-NMR methods). The formation of 7 via 1,2-H shift and subsequent isomerization to 8 has been studied. The esters 11 and 13 are formed stereospecifically from 7 and 8 . 相似文献
32.
Presenting a condensation of the opening lecture of the 12th ICFIA conference, this communication presents a view of the impact that flow injection analysis (FIA) has had on modern analytical chemistry, evaluated both within the academic community and outside it, i.e. in “industry”. The ensuing developments of FIA, encompassing sequential injection analysis (SIA) and bead injection lab-on-valve (BI-LOV), are described and their individual features discussed. Finally, some recent results of the activities from the author’s own research group are briefly mentioned. 相似文献
33.
Saalfrank RW Deutscher C Maid H Ako AM Sperner S Nakajima T Bauer W Hampel F Hess BA van Eikema Hommes NJ Puchta R Heinemann FW 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(8):1899-1905
In the reaction of the N-substituted diethanolamines (H(2)L(1-3)) (1-3) with calcium hydride followed by addition of iron(III) or indium(III) chloride, the iron wheels [Fe(6)Cl(6)(L(1))(6)] (4) and [Fe(6)Cl(6)(L(2))(6)] (6) or indium wheels [In(6)Cl(6)(L(1))(6)] (5), [In(6)Cl(6)(L(2))(6)] (8) and [In(6)Cl(6)(L(3))(6)] (9) were formed in excellent yields. Exchange of the chloride ions of 6 by thiocyanate ions afforded [Fe(6)(SCN)(6)(L(2))(6)] (7). Whereas the structures of 4, 5 and 7 were determined unequivocally by single-crystal X-ray analyses, complexes 8 and 9 were characterised by NMR spectroscopy. Contrary to what is normally presumed, the scaffolds of six-membered metallic wheels are not generally rigid, but rather undergo nondissociative topomerisation processes. This was shown by variable temperature (VT) (1)H NMR spectroscopy for the indium wheel [In(6)Cl(6)(L(1))(6)] (5) and is highlighted for the enantiotopomerisation of one indium centre [ 1/6[S(6)-5]<==>[1/6[S(6)-5']]. The self-assembly of metallic wheels, starting from diethanolamine dendrons, is an efficient strategy for the convergent synthesis of metallodendrimers. 相似文献
34.
On the Reaction of Nb3Cl8 with HCl The greenish-blue gas phase which is formed at 500–600°C by reaction of Nb3Cl8 with HCl, is caused by an equilibrium reaction, in which small amounts of NbCl5 and larger amounts of NbCl4 are formed. This is shown by photometric measurements and by thermodynamic calculations. 相似文献
35.
Harald Stueger Markus Braunwarth Gottfried Fuerpass Judith Baumgartner Robert Saf 《Monatshefte für Chemie / Chemical Monthly》2006,137(5):595-603
Summary. The previously unknown ruthenio disilanes Rp–Si2Me4–C6H4X (Rp = η5-C5H5Ru(CO)2; X = H, Br, –CHO, CH=C(CN)2) were synthesized from ClSi2Me4C6H4X (X = H, Br) and Rp− using conventional chemical methods. Trends in the UV/Vis absorption spectra indicate strong electronic coupling within the
Rp–Si–Si–Caryl fragment and, therefore, closely resemble the ones observed for the corresponding iron complexes. The four compounds however,
were shown to be less sensitive towards UV irradiation. The crystal structure of Rp–Si2Me4–C6H4CH=C(CN)2 was determined by X-ray diffraction and exhibits an all-trans-array of the Ru–Si–Si–Caryl moiety, what is a basic requirement for optimal through-bond interaction. 相似文献
36.
At a pressure of 10?6 Torr the ion cyclotron resonance spectra of p-benzoquinone, methyl-p-benzoquinone, tetramethyl-p-benzoquinone and tetrafluoro-p-benzoquinone are identical to the normal mass spectra. Above 10?5 Torr the spectra show a variety of signals for product ions. From double resonance measurements it was shown that all the product ions are formed by addition of the molecular ion or of a fragment ion to a neutral quinone molecule. In most cases the addition is accompanied by the elimination of carbon monoxide. 相似文献
37.
Harald Löwe 《Geometriae Dedicata》1995,58(1):45-51
We construct symmetric planes associated with an arbitrary locally compact connected nearfield
. If
is a proper nearfield, i.e.
{;;}, then the tangent translation plane of this symmetric plane is not classical. All previously known examples of symmetric planes have classical tangent translation planes.Herrn Professor Dr. H. Salzmann zum 65. Geburtstag gewidmet 相似文献
38.
Vaporization of Silver in a Stream of Oxygen Using a transport equipment the vaporization of silver at 611–721°C in a stream of oxygen has been measured. Experiments with detachable cuffs of silver or with wools of silver in a bulb made from quartzglass or silver lead to the same results. By variation of the O2-pressure and the activity of silver is observed that the vaporization happens as Ag2O,g, see “Inhaltsübersicht”. The solid was at first pure silver. During long lasting experiments, however, it is covered with a thin layer of oxygen or silver oxide, which lowers the concentration of Ag2O,g in the equilibrium gas to a smaller, yet constant value. The following measurements using N2 as carrier gas lead to the decomposition of this layer and ends with the very small vapor pressure of silver. The layer of oxygen or silver oxide on the metal could be shown after Davies [2] using mercury. 相似文献
39.
The change in fluorescence quantum yield for indole as a function of excitation wavelength between 250 and 220 nm is found to vary with the static dielectric constant of various alcohol—water mixtures at 296 K. The supports the intermediacy of a CTTS state in the photoionization process. 相似文献
40.
Harald Rotzsche und Harald Rösler 《Fresenius' Journal of Analytical Chemistry》1961,181(1):407-417
Zusammenfassung Bei der Herstellung von Siliconkautschuk verursachte eine uns nicht bekannte Komponente im Ausgangsmaterial Octamethylcyclotetrasiloxan Schwierigkeiten. Es traten bei der Polymerisation mitunter unerwünschte Vernetzungen auf. Gaschromatographisch wurde festgestellt, daß das Vorprodukt Dimethyldichlorsilan noch Methylhydrodichlorsilan enthielt. In dem aus einem solchen Dimethyldichlorsilan hergestellten Octamethylcyclotetrasiloxan fanden wir ebenfalls gaschromatographisch zwischen 0,02 und 0,2% einer uns nicht bekannten Substanz, die an Silicium gebundenen Wasserstoff aufwies. Die gleiche Substanz konnte durch Cohydrolyse der beiden Chlorsilane neben anderen cyclischen Verbindungen dargestellt und isoliert werden. Ihr Retentionsvolumen wurde unter anderem an der Verteilungsflüssigkeit Siliconöl DC 703 bestimmt. Trug man die Logarithmen der Retentionsvolumina dieser cyclischen Verbindungen als Funktion des Molgewichtes auf, so zeigte sich, daß es sich bei dem störenden Bestandteil um Heptamethylcyclotetrasiloxan handelte. An Modellgemischen wurde festgestellt, daß diese Verbindung die D4-Polymerisation tatsächlich stört.Auf die gleiche Weise konnte eine Reihe anderer, bisher noch nicht beschriebener Cyclosiloxane mit Si-H-Bindungen in dem Cohydrolysat aus (CH3)2SiCl2 und CH3HSiCl2 festgestellt werden. In einer Tabelle sind die effektiven und relativen Retentionsvolumina von 18 Cyclosiloxanen angegeben.Bei mehreren dieser Verbindungen sind diese gaschromatographischen Kennzahlen die ersten gemessenen physikalisch-chemischen Daten, da die Mehrzahl der Methylhydrocyclosiloxane noch nicht in reiner Form isoliert worden ist.50. Mitteilung: Rich. Müller, R. Köhne u. S. Sliwinski, J. prakt. Chem., [4] 11, 336 (1960). 相似文献