Beiträge zur Chemie des Sulfamids, 1. Mitt.: Zur Konstitution des Disilber-sulfamids

According to spectroscopic (IR, broadline proton NMR) and chemical (alkylation) investigations of disilver sulphamide the following molecular structure is assumed: $$\begin{gathered} O \hfill \\ || \hfill \\ H_2 N\_\_S\_\_NAg| \hfill \\ OAg \hfill \\ \end{gathered}$$ From the IR and NMR data deduction concerning the nature of the chemical bonds in this compound is possible. The instability of the still unknown mono-and trisilver sulphamide is discussed with regard to the structure of disilver sulphamide.     

Über die Konfiguration des Prolins im Ergotamin

It is well known that in the ergot alkaloids of the peptide type the proline appears in thel-configuration. Different methods of acid hydrolysis may lead to various cleavage products; hydrolysis by HCl yieldsd-proline, on the other hand hydrolytic cleavage by means of strongly acid cation exchange resin preserved the orginall-configuration.

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Teilveröffentlichung der Dissertation vonH. Kolassa, Univ. Wien, 1973.     

Thermische Polymerisation von Acenaphthylen

Zusammenfassung Acenaphthylen wurde durch Anpolymerisation und zweifache Hochvakuumsublimation gereinigt. Die Reinigungsmethode wird ausführlich beschrieben.Bei verschiedenen Temperaturen wurde mit einer dilatometrischen Methode die thermische Bruttogeschwindigkeit gemessen. Zwischen 95 und 105 °C giltk _br=7,0₈·10¹⁰ exp (– 30,9 kcal/RT).Die beträchtliche Aktivierungsenergie der Bruttoreaktion ist sowohl auf eine große Aktivierungsenergie der thermischen Startreaktion als auch auf eine relativ hohe Wachstumsaktivierungsenergie zurückzuführen.Das Polymerisationsverhalten von Acenaphthylen kann vermutlich aufgrund seiner sterischen Eigenschaften erklärt werden.

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Summary Acenaphthylene was purified by partial polymerisation, followed by double stage high vacuum sublimation. The method of purification is described in detail.The thermal overall rate was measured at different temperatures by a dilatometric method. Between 95 and 105 °C the following relation holds:k _th=7,0₈ · 10¹⁰ exp (– 30,9 kcal/RT).The considerable energy of activation of the overall reaction depends on a relatively high energy of activation of both the thermal initiation and the propagation reaction.It is supposed, that the polymerisation behaviour of acenaphthylene depends mainly on its steric properties.

     

Improved flask-combustion method for phosphorus in petroleum products

Summary An electrical assembly for the oxygen-flask combustion of lubricants and similar petroleum products is described. The pyrolysis is performed in two consecutive steps. After the ignition and burning of the sample (sorbed on sodium carbonate) the combustion is completed by further heating. The sample weight should not exceed 140 mg. In this way the sensitivity of phosphorus determination of the tentative IP standard procedure is enhanced from 0.01 to 0.001% phosphorus if the volume of solution for the final spectrophotometric measurement is reduced.

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Zusammenfassung Ein elektrisches Gerät für die Verbrennung von Schmierölen und ähnlichen Erdölprodukten im Schöniger-Kolben wurde beschrieben. Die Pyrolyse erfolgt in zwei aufeinander folgenden Schritten. Nach der Entflammung der an Natriumcarbonat adsorbierten Probe und nach Erlöschen der Flamme erfolgt die vollständige Verbrennung von Einwaagen, die 140 mg nicht überschreiten. So konnte die Empfindlichkeit der Phosphorbestimmung nach der tentativen IP-Standardmethode von 0,01% auf 0,001% Phosphor gesteigert werden, wenn man die spektrophotometrische Messung mit vermindertem Lösungsvolumen durchführt.

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Herrn Professor Dr. H. Lieb zum 90. Geburtstag gewidmet.     

Das Schwingungsspektrum von Magnesium-orthovanadat

The infrared and laser-Raman spectra of crystalline Mg₃(VO₄)₂ are reported and a factor group analysis for the full lattice is presented to support the discussion. The 1,000 to 600 cm^?1 region of the spectrum is essentially related to internal (stretching) modes of the greatly distorted VO₄ tetrahedra, whereas the bands in the low frequency region must be assigned to complex vibrations originating in the interaction of the bending vibrations of the tetrahedral groups with the external modes.     

Das dielektrische Verhalten von Polyäthern zwischen Mikrowellen- und Infrarot-Gebiet

Zusammenfassung Es wurde die Absorption und Dispersion verschiedener Polyäther im Mikrowellengebiet und im fernen IR untersucht. Mit wachsender Sauerstoffzahl in der Kette werden die Torsions- und Biegeschwingungen wachsend IR-aktiv. Ihre Frequenzlagen ändern sich mit dem zunehmend polaren Charakter der Struktur. Die Analogie zwischen der Verschiebung der Schwingungsfrequenzen und dem Verlauf der Schmelztemperaturen wird diskutiert.Mit zunehmend polarem Charakter steigen der Temperaturkoeffizient der Molpolarisation und die Differenz (–n ²) der Dielektrizitätskonstanten im Mikrowellengebiet und im optischen Bereich stark an. Ein Vergleich mit der Höhe der Dispersionsstufen im fernen IR und deren Temperaturabhängigkeit ergab, daß diese zusätzliche Polarisation nicht allein durch die IR-aktiven Banden bedingt ist. Sie muß gekoppelt sein mit dem ebenfalls stark anwachsenden Untergrundverlust im gesamten mm- und sub-mm-Gebiet.

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Summary Absorption and dispersion of several polyethers were measured in the microwave region and in the far infrared. The torsional vibrations become increasingly iractive with increasing number of oxygens in the chain. Their frequencies shift, too, in a manner analogues to the variation of the melting temperatures.The temperature coefficient of the mol polarization at 32 GHz and the difference (–n ²) between microwave and optical dielectric constant rise rapidly with increasing polar character of the structure. It was tried to correlate (–n ²) with the overall absorption of the skeletal vibrations. Height and temperature dependence of the far ir dispersion show, however, that the larger part of this additional polarization cannot be accounted for by the resonance absorption bands. It must be correlated with the background loss which extends over the whole mm and sub-mm range and also increases rapidly with increasingly polar structure.

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Mit 10 Abbildungen in 14 Einzeldarstellungen und 2 Tabellen     

Formation and Crystal Structure of [(F5TeOXe)+·SO2ClF][Sb(OTeF5)6-]

Xe(OTeF₅)₂ reacts with Sb(OTeF₅)₃ under the formation of [Xe₂(OTeF₅)₃]⁺[Sb(OTeF₅)₆]^-. From SO₂ClF solution a yellow solvate [F₅TeOXe]⁺·SO₂ClF· [Sb(OTeF₅)₆]^- is formed with the crystal data: a = 1028.1(1), b = 1040.9(1), c = 1780.2(3) pm, α = 98.07(1), β = 97.68(1), γ = 105.82(1)°, space group . The O-Xe···O fragment is essentially linear (176.1(2)°), and the two Xe-O distances are quite different 197.1(4) and 242.6(4) pm.     

Probing the kinetic landscape of transient peptide-protein interactions by use of peptide (15)n NMR relaxation dispersion spectroscopy: binding of an antithrombin peptide to human prothrombin

Protein-ligand interactions may lead to the formation of multiple molecular complexes in dynamic exchange, affecting the kinetic and thermodynamic characteristics of the binding equilibrium. We followed the dissociation kinetics of the transient and specific complex of an antithrombotic peptide N-acetyl-Asp(55)-Phe-Glu-Glu-Ile-Pro(60)-Glu-Glu-Tyr-Leu-Gln(65) with human prothrombin by use of (15)N NMR relaxation dispersion spectroscopy of the peptide. Every one of the five (15)N-labeled adjacent residues of the peptide exhibited apparently different kinetic exchange and relaxation behaviors, which were especially evident at different concentrations of prothrombin. Binding-induced (15)N relaxation dispersion of residues Phe(56), Glu(57), Glu(58), and Ile(59) can be fitted phenomenologically to a two-site on-and-off exchange mechanism with physically feasible relaxation and kinetic parameters obtained for residues Phe(56), Glu(58), and Ile(59), independent of the prothrombin concentration. The apparent kinetic parameters of Glu(57) show some dependence on the concentration of prothrombin and the extracted transverse relaxation rate for Glu(57) in the bound state was severalfold higher than that expected for a protein-peptide complex with a size of approximately 72 kDa. In addition, the equilibrium population of the bound peptide obtained for Glu(57) was inconsistent with those for Phe(56), Glu(58), and Ile(59) and with the prothrombin/peptide ratios used in the experiments. These discrepancies can be explained by the presence of two conformations for the peptide-protein complex exchanging at a rate of approximately 100 s(-)(1). In all, our study shows that fast dissociation of protein-peptide complexes can be studied quantitatively using peptide (15)N NMR relaxation dispersion measurements without a precise knowledge of the peptide and protein concentrations. In addition, protein titration was found to improve the accuracy of quantitative analysis and may make it possible to determine the rate of conformational changes within the protein-peptide complex.