Stereochemie von Metallocenen, 10. Mitt.: Chemische Korrelation von α- und β-substituierten Methylferrocenen; die absolute Konfiguration optisch aktiver, β-substituierter Methyl- und 1.1′-Dimethylferrocene

Zusammenfassung Optisch aktive Methylferrocen-- und--carbonsäuren wurden über die entsprechenden isomeren Methylferroceno[1.2]-cyclohexenone (7, 12 und15, deren Struktur u. a. durchNMR geklärt wurde) und über ein aktives Methylferroceno-cyclohexen (8) bezüglich ihrer Konfigurationen chemische korreliert. ORD-Vergleiche der methylierten Ringketone mit Ferrocenocyclohexenon (10), dessen Konfiguration bekannt war, erlaubten einen sicheren Schluß auf die Konfigurationen aller - und -substituierten Methylferrocene: (1S) für die rechtsdrehenden Säuren und ihre Derivate. Dies konnte auch durch unabhängige Konfigurationsermittlung eines der Ringketone (12) bestätigt werden.Es sind damit die absoluten Konfigurationen von insgesamt 86 optisch aktiven - und -substituierten Ferrocenderivaten bekannt; alle Konfigurationen sind jetzt eindeutig miteinander verknüpft.

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Optically active methylferrocene-- and--carboxylic acids were configurationally correlated by chemical methodsvia the corresponding isomeric methylferroceno[1.2]cyclohexenones (7, 12 and15, the structures of which were elucidated among other methods byNMR) andvia an optically active methylferrocenocyclohexene (8).Comparison of theORD-curves of the methylated ringketones with ferrocenocyclohexenone (10), the configuration of which was known, allowed a reliable conclusion to the configurations of all - and -substituted methylferrocenes: (1S) for the dextrorotatory carboxylic acids and their derivatives. This result could also be confirmed by an independent determination of the configuration of one of the ring ketones (12).Thereby, the absolute configurations of 86 optically active - and -substituted ferrocenederivatives are known; all configurations have now been unambiguously correlated.

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Mit 2 Abbildungen

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9. Mitt. (34. Mitt. über Ferrocenderivate):G. Haller undK. Schlögl, Mh. Chem.98, 603 (1967).     

Synthese von 3-Hydroxy-1-oxo-4-alkyl-1H-benzo[d]pyrido[2,1—b]thiazolen

Zusammenfassung -[Benzothiazolyl-(2)]-acetessigsäurealkylester können zu Benzopyridothiazolen cyclisiert werden. Bei Umsetzung solcher substituierter Acetessigester mit Alkylhalogeniden in Gegenwart von Basen erfolgt Cyclisierung zu Benzopyridothiazolen, die an C-4 alkylsubstituiert sind. IR- und¹H-NMR-Daten dieser Heterocyclen und einiger ihrer Derivate werden mitgeteilt.

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Synthesis of 3-hydroxy-1-oxo-4-alkyl-1H-benzo[d]pyrido-[2.1—b]thiazoles

Ring closure of -[benzothiazolyl-(2)]-acetoacetates affords benzopyridothiazoles. In the reaction of these substituted acetoacetic acid esters with alkyl halides in the presence of bases, the formation of benzopyridothiazoles is observed; these heterocyclic compounds are alkyl-substituted at C-4. IR- and¹H-NMR-spectral data of the benzopyridothiazoles and some of their derivatives are given.

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Aus der DissertationN. Hawlitzky, Freiburg im Breisgau, 1970.     

Two-mode jahn-teller effect in nh+3

The two-mode E ? (? + ?) Jahn-Teller effect in NH⁺₃ is investigated theoretically. Using ab initio coupling constants, it is shown that the inclusion of the interaction between the degenerate stretching and bending vibrational modes is essential for understanding the experimental findings. An effective single-mode Jann-Teller hamiltonian is introduced to simulate the more complicated two-mode problem. Although such a hamiltonian cannot be expected to reproduce the details of the vibrational structure, it is generally found to reproduce the band shape of unresolved spectra most accurately.     

Erratum

Ohne Zusammenfassung

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Erratum

     

A self-silenced sound beam

Parametric loudspeakers are transmitting two high power ultrasound frequencies. During propagation through the air, nonlinear interaction creates a narrow sound beam at the difference frequency, similar to a light beam from a torch. In this work is added the physical phenomenon of propagation cancellation, leaving a limited region within which the sound can be heard—a 1 meter long cylinder with diameter 8 cm. It is equivalent to a torch which would only illuminate objects within 1 meter. The concept is demonstrated both in simulation and in experiment.     

Optical detection and ionization of donors in specific electronic and nuclear spin States

We resolve the remarkably sharp bound exciton transitions of highly enriched 28Si using a single-frequency laser and photoluminescence excitation spectroscopy, as well as photocurrent spectroscopy. Well-resolved doublets in the spectrum of the 31P donor reflect the hyperfine coupling of the electronic and nuclear donor spins. The optical detection of the nuclear spin state, and selective pumping and ionization of donors in specific electronic and nuclear spin states, suggests a number of new possibilities which could be useful for the realization of silicon-based quantum computers.     

Solubility Thermodynamics of CyMe$$_{}$$-BTBP in Various Diluents Mixed with TBP

The two organic ligands 6,6′-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenzo[1,2,4]triazin-3-yl)[2,2′]bipyridine (CyMe\(_{4}\)-BTBP) and tri-butyl phosphate (TBP) have previously been investigated in different diluents for use within recycling of used nuclear fuel through solvent extraction. The thermodynamic parameters, \(K_{\mathrm{S}}\), \(\Delta C_{p}\), \(\Delta H^{0}\) and \(\Delta S^{0}\), of the CyMe\(_{4}\)-BTBP solubility in three diluents (cyclohexanone, octanol and phenyl trifluoromethyl sulfone) mixed with TBP have been studied at 288, 298 and 308 K, both as pristine solutions and pre-equilibrated with 4 mol\(\cdot \)L\(^{-1}\) nitric acid. In addition, the amount of acid in the organic phase and density change after pre-equilibration have been measured. The solubility of CyMe\(_{4}\)-BTBP increases with an increased temperature in all systems, especially after acid pre-equilibration. This increased CyMe\(_{4}\)-BTBP solubility after pre-equilibration could be explained by acid dissolution into the solvent. Comparing the \(\Delta H^{0}\) and \(\Delta S^{0}\) calculated using \(\Delta C_{p}\) with the same parameters derived from a linear fit indicates temperature independence of all three thermodynamic systems. The change in enthalpy is positive in all solutions.     

Cellulose

Ohne Zusammenfassung     

Critical fluctuations of the micellar triethylene glycol monoheptyl ether-water system

Using the equal volume criterion and also the pseudospinodal conception the critical demixing point of the triethylene glycol monoheptyl ether/water system (C7E3H2O) has been determined as Ycrit=0.1 and Tcrit=296.46 K (Y, mass fraction of surfactant). From density measurements the critical micelle concentration (cmc) followed as Ycmc=0.007 at 288.15 K and Ycmc=0.0066 at 298.15 K. The (static) shear viscosity etas and the mutual diffusion coefficient D of the C7E3H2O mixture of critical composition have been evaluated to yield their singular and background parts. From a combined treatment of both quantities the relaxation rate Gamma of order parameter fluctuations has been derived. Gamma follows power law with universal critical exponent and amplitude Gamma0=3.1 x 10(9) s(-1). Broadband ultrasonic spectra of C7E3H2O mixtures exhibit a noncritical relaxation, reflecting the monomer exchange between micelles and the suspending phase, and a critical term due to concentration fluctuations. The former is subject to a relaxation time distribution that broadens when approaching the critical temperature. The latter can be well represented with the aid of the dynamic scaling model by Bhattacharjee and Ferrell (BF) [Phys. Rev. A. 31, 1788 (1985)]. The half-attenuation frequency in the scaling function of the latter model is noticeably smaller (Omega12 (BF) approximately 1) than the theoretically predicted value Omega12 (BF)=2.1. This result has been taken as an indication of a coupling between the fluctuations in the local concentration and the kinetics of micelle formation, in correspondence with the idea of a fluctuation controlled monomer exchange [T. Telgmann and U. Kaatze, Langmuir 18, 3068 (2002)].