First osmium-catalysed ketamination of alkenes

Conditions for a first oxidative conversion of alkenes into 2-amino ketones are described, which yield racemic products within a direct oxidation pathway and 2-amino ketones with up to 99% enantiomeric excess from the corresponding enantiopure amino alcohols.     

Measurement of the η production in proton-proton collisions with the COSY time-of-flight spectrometer

The reaction pp → ppη was measured at excess energies of 15 and 41 MeV at an external target of the Jülich Cooler Synchrotron COSY with the time-of-flight spectrometer. About 25000 events were measured for the excess energy of 15 MeV and about 8000 for 41 MeV. Both protons of the process ppη were detected with an acceptance of nearly 100% and the η was reconstructed by the missing-mass technique. For both excess energies the angular distributions are found to be nearly isotropic. In the invariant-mass distributions strong deviations from the pure phase space distributions are seen. Received: 24 May 2002 / Accepted: 20 September 2002 / Published online: 17 January 2003 RID="a" ID="a"e-mail: e.roderburg@fz-juelich.de Communicated by M. Gar?on     

Palladium(II)-catalyzed intramolecular diamination of unfunctionalized alkenes

Intramolecular diamination reactions are described which yield cyclic ureas as direct products of an oxidative alkene transformation in the presence of palladium acetate and iodosobenzene diacetate as terminal oxidant. The reaction is truly catalytic in metal catalyst and represents the proof of principle for this elusive type of alkene oxidation.     

Isobaric binary state diagrams ofn-alkanes

Isobaric state diagrams of various binaryn-alkane mixtures have been derived from DTA-measurements. They can be described by means of proper thermodynamic relations which are essentially taking into consideration the disparity in chain lengths. The discussion of the thermodynamic parameters is elucidating the physical situation in the longitudinal boundaries of extended mixed crystals such that stability conditions in binaryn-alkane systems can be developed. Occurrence of eutectical crystallization in the binary mixtures can fairly well be predicted dependend upon the relative disparity in chain lengths.Dedicated to Prof. Dr. F. H. Müller.     

Thermomechanics of bimodal end-linked polydimethylsiloxane networks with one of the chains much short

Summary A novel equation of state for bimodal networks with extremely short chains as solid intrusions is developed proceeding from the van der Waals theory of molecular networks. Stress-strain and thermoelastic measurements on bimodal end-linked polydimethylsiloxane model networks can satisfactorily be described. The physical reasons behind that representation will be discussed.Dedicated to Professor Dr. K. Ueberreiter on his 70th birthday.     

Spectroscopy of the hypernucleus Λ12C

Kaons were stopped in a ¹²C target. The momenta of pions accompanying the kaon interactions were measured with a magnetic spectrometer. States in _Λ¹²C with binding energies of the Λ particle of 11 ± 1 MeV and 0 ± 1 MeV have been observed.     

DasK/β+-Verhältnis beim Zerfall J128→T128

In the decay of J¹²⁸ the intensity of a weak positron activity was measured to be (3.1±0.7)·10^?5 per disintegration. The remeasurement of the totalK capture was found to be 0.059±0.007 in agreement with the results of other authors. From this theK/β ⁺-ratio of the decay to the ground state of Te¹²⁸ is 1800±400. Theoretical calculations ofK/β ⁺ for allowed transitions show that the maximum energy of the positrons is 245±12 keV. In the decay of Rh¹⁰⁴ and Lu^176m no positrons more than 5·10^?6 could be detected.     

Die morphologische Struktur von Copolymeren des Äthylens abhängig von den Gegebenheiten des Molekülbaues

Zusammenfassung Elektronenmikroskopische Aufnahmen an Copolymeren des Äthylens belegen im Beispiel lösungskristallisierter Proben in Übereinstimmung mit einfachen theoretischen Überlegungen, daß das morphologische Erscheinungsbild mit wachsender Unregelmäßigkeit im Molekülbau aus einem lamellar-regelmäßigen Typ in unregelmäßige flüssigkeitsähnliche Strukturen übergeht. Für schmelzkristallisierte Proben muß man ähnliche Gesetzmäßigkeiten erwarten, wenn der Kristallanteil sowie die Verteilung der Kristalle einschließlich deren Größenstatistik sich im morphologischen Erscheinungsbild ausdrücken sollen. Man findet an Oberflächen schmelzkristallisierter Filme jedoch nur einen sehr losen Zusammenhang mit den genannten Überstrukturdaten. Erst Bruchflächenabdrücke verifizieren die erwarteten Sachverhalte.Wir danken der Deutschen Forschungsgemeinschaft und dem Verband der Chemischen Industrie e.V. für die großzügige Bewilligung von Sach- und Personalmitteln.