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91.
1,3-Dienes and electron deficient alkenes are coupled in a one pot carbon-carbon bond formation reaction under mild conditions. 相似文献
92.
93.
The acid catalysed dienone-phenol rearrangement of methyl substituted o-propargyl-cyclohexadienones (scheme 3) was investigated. The rearrangements were carried out in acetic anhydride containing about 10/00 sulfuric acid. Under these conditions acetoxy benzenium ions are formed as intermediates. These then undergo charge-controlled [3s, 4s]- and [1s, 2s]-sigmatropic rearrangements. Thus, the [3s, 4s]-process leads to the formation of the corresponding allenyl-phenol acetates ( 19 , 21 , 23 , 25 , 28 , 30 ) whereas the [1s, 2s]-process yields propargyl-phenol acetates ( 20 , 22 , 24 , 26 , 29 ), respectively (cf. scheme 4). 相似文献
94.
Josef Edinger Heinz Falk Walter Jungwirth Norbert Müller Ulrich Zrunek 《Monatshefte für Chemie / Chemical Monthly》1984,115(8-9):1081-1099
From an investigation of the ICD of bilatrienes-abc and 2,3-dihydrobilatrienes-abc induced by mixtures of CCl4 with (+)-cis-Pinane, (–)-lactic and (+)-tartaric acid esters it is concluded that specific interactions between chromophore and the chiral reagents afford a partial resolution of the labile racemate of helices. Attaching chiral residues covalently to the chromophore induces very low resolution of the same kind in case of apolar ligands like a cholesteryl-residue. However, with polar ligands as in the case ofBoc-lysyl derivatives enantiomeric excesses up to 90% are achieved depending on the solvent used.
Herrn Prof. Dr.Karl Schlögl zu seinem 60. Geburtstag gewidmet. 相似文献
95.
The thioketene iron cluster (CH3)4C6H6CS(PPh3)2(CO)4Fe2S (I) reacts with thioketene in excess quantitatively to a vinylidene complex, as confirmed by X-ray analysis. 相似文献
96.
The application of solid layer crystallization techniques in industry is arousing ever more interest. One reason is the increasing demand for ultrapure products, and another is the energysaving potential of this separation technology.This article examines solid layer melt crystallization as concerns its purification efficiency. The crystallization process was carried out in two different modes, whereby the process parameters were varied and post-crystallization treatments were additionally applied. The experimental results were used as the basis for a mathematical fit of a semi-empirical expression which predicts the purification efficiency. It was used for a design of different multistage plants, which operate with different crystallization strategies. One result is that a comparable product quality is attainable with a simple process technique in combination with post-crystallization treatments, instead of a more complicated and therefore more expensive process technique.The authors wish to acknowledge support by the EU (JOULE program), which helped attainment of some results presented here. 相似文献
97.
Christoph Kratky Heinz Falk Ulrich Zrunek 《Monatshefte für Chemie / Chemical Monthly》1985,116(5):607-623
The molecular and crystal structures of the two racemic diastereomeric 3,4-dihydropyrromethenone derivatives1 and2 of configurations (Z) and (E) were determined at 93 K (1, 2) and at room temperature (1). From an analysis of the crystallographically observed temperature coefficients a pseudorotation flexibility of the pyrrolidinone ring in the crystal is deduced. In both compounds a nearly orthogonal arrangement between the two heterocyclic ring systems is observed, which is ascribed to the steric bulk of the substituents in positions 1 and 3 of the pyrrolidinone ring.Herrn Prof.Josef Schurz zum 60. Geburtstag gewidmet. 相似文献
98.
Novel Inorganic Ring Systems. 34. Derivatives of the Cyclo-1-thiaIV- and of the Cyclo-1-thia VI-3,4-disila-2,5-diazane Variations of fivemembered “hetero” cyclosilazanes of the type Si2N2El could be enlarged to the systems with El = SO and SO2. They are obtained by the formation principles 4 + 1 and 2 + 3 respectively, according to the equation (1), (4) and (5). The prepared compound are described in their properties and confirmed in their structure (Tables 1–2). 相似文献
99.
Ulrich Heber 《Fresenius' Journal of Analytical Chemistry》1958,161(6):409-421
Zusammenfassung Es wird ein neues, leicht herstellbares Gerät beschrieben, mit dem Transmissions- und Remissionsmessungen an papierchromatographischen Flecken zur quantitativen Auswertung durchgeführt werden können. Das Gerät ist auch für andere Zwecke brauchbar, ist aber vor allen Dingen für genaue Serienuntersuchungen an biologischem Material entwickelt worden. Die Fehlergrenze liegt bei etwa ± 3% (bei 100 g Galaktose und Anilinphthalatentwicklung). Theoretische Grundlagen werden aufgezeigt und diskutiert. An Stelle des Lambert-Beerschen Gesetzes wird eine Beziehung mit weiterem Gültigkeitsbereich für die Auswertung von Transmissionsmessungen an Papieren erörtert.Für reges Interesse an der Arbeit und stete Förderung bin ich den Herren Prof. Dr. H. Ullrich vom Institut für Landwirtschaftliche Botanik und Prof. Dr. B. Helferich vom Chemischen Institut der Universität Bonn zu außerordentlichem Dank verpflichtet. Die Untersuchungen sind zum Teil aus Mitteln der Deutschen Forschungsgemeinschaft bestritten worden, wofür hier noch besonders gedankt sei. 相似文献
100.
A rigid terpyridine ligand containing chiral alkyl chains has been synthesized, characterized and subsequently complexed with ruthenium(II) ions. The product was characterized by MALDI-TOF-MS, UV-vis and NMR. Circular dichroism showed the appearance of extended helical columnar aggregates. 相似文献