Über den mikroanalytischen Nachweis mechanochemischer Reaktionen

Zusammenfassung Einige Mechanochemische Reaktionen lassen sich auf einfache Weise mikroanalytisch nachweisen. So wurden die beim Verreiben von fein kristallinem Calciumcarbonat, Calcit, Dolomit oder beim Verreiben von Schwefel mit Eisenpulver erfolgenden Reaktionen schon nach wenigen Sekunden der mechanischen Einwirkung festgestellt.

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Summary Several mechano-chemical reactions can be detected by simple micro-analytical methods. For example, the reactions brought about by grinding finely crystalline calcium carbonate, calcite, dolomite, or by grinding sulfur with powdered iron can be established after a few seconds of mechanical action.

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Résumé Quelques réactions mécaniques-chimiques peuvent être identifiées simplement par microanalyse. C'est ainsi que les réactions qui se produisent en malaxant de fins cristaux de carbonate de calcium, de calcite, de dolomite, ou encore en malaxant du soufre avec de la poudre de fer, peuvent être mises en évidence quelques secondes après l'action mécanique.

     

13C spin relaxation studies of the basic pancreatic trypsin inhibitor

The longitudinal ¹³C spin relaxation times T₁ and the ¹³C{¹H} nuclear Overhauser enhancement were measured in a concentrated aqueous solution of the basic pancreatic trypsin inhibitor. The correlation time for overall rotational motions of the basic pancreatic trypsin inhibitor molecules was found to be τ_R ≈ 2 × 10^?8 s. In connection with previous ¹H n.m.r. studies of intramolecular motions of the aromatics, we were particularly interested in the correlation times τ_G for intramolecular segmental motions of the aromatic rings. The present experiments revealed no manifestation of intramolecular motions of the aromatics, indicating that τ_G ? 2 × 10^?8 s for the aromatic ring carbon atoms. On the other hand, rapid segmental motions were evidenced for the peripheral carbon atoms of aliphatic amino acid sidechains. Comparison of the ¹H and ¹³C n.m.r. data on the basic pancreatic trypsin inhibitor indicates that the time scale of high resolution ¹H n.m.r. at high fields may in many instances be more appropriate for studies of the molecular dynamics in globular proteins than the time scale of spin relaxation measurements.     

Fluordiazadiphosphetidine, 7. Mitt. Die reaktion von 2,2,2,4,4,4-Hexafluoro-1,3-dimethyl-1,3,2λ5,4λ5-diazadiphosphetidin mit mono-und bissilyliertemN,N′-Dimethylharnstoff

The reaction of (CH₃NPF₃)₂ with mono-and bissilylatedN,N-dimethylurea yields a crystalline solid which has been identified as a cuban-like P-N-compound with two dimethylurea-bridges. The conditions of formation and the NMR-spectra are discussed.

     

Zur Photochemie von Δ1,9-10-Methyl-2-octalon

Some aspects of the photochemistry of Δ^1,9-10-methyl-2-octalone ( 1 ) were reinvestigated. In view of the hitherto neglected substantial thermal reversibility of the photolytic double bond shift under previous conditions of analysis (1) the solvent-dependent selectivity in product formation in C₆H₆ and t-BuOH was confirmed, (2) the essentially exclusive double bond shift and its intermolecular nature in C₆F₆ were established, (3) the quantum yields of the major products in these three solvents were measured, and (4) the dependence of triplet quenching data on temperature, enone concentration and conversion was shown in C₆F₆ for the double bond shift. In conclusion, the previously published experimental basis for the postulate of two differentially reactive triplet states of 1 is insufficient, although the postulate itself is not necessarily disproved.     

Elementare Berechnung von kubischen Diskriminanten

Ohne Zusammenfassung     

Einfluß von Magnesiumnitrat auf die Trennung von Ytterednitraten in großem Maßstab durch thermische Zersetzung mit nachfolgender stufenweiser Hydrolyse

Summary The separation was studied in the presence of magnesium nitrate and compared with the separation in its absence. As a useful criterion served the expressionA/Z (part of Er in precipitate divided by the degree of decomposition). Under all conditions the separation was significantly better in the presence of magnesium nitrate. The method was used to concentrate the heavy yttrium earths (YE) Er, Tm, Yb and Lu from 38 kg to 10 kgYE ₂O₃.

     

Niobpentachlorid-Thiazylchlorid-Addukt Darstellung,Schwingungsspektrum und Kristallstruktur

Complex of Niobium Pentachloride with Thiazyl Chloride Preparation, Vibrational Spectrum, and Crystal Structure Niobium pentachloride reacts with trithiazylchloride in CCl₄-suspension forming the complex Cl₅Nb? NSCl which forms red crystals that are very sensitive to moisture. According to the vibrational spectrum and the crystal structure determination the compound consists of monomeric units in which NbCl₅ is bonded to N?S? Cl in a relatively loose manner via the nitrogen atom. The crystal structure was determined with X-ray diffraction data and was refined to a residual index of R = 0.019 for 1879 reflexions. Cl₅NbNSCl crystallizes in the triclinic space group P1 with the lattice constants a = 636.7, b = 1215.5, c = 1266.8 pm, α = 83.32, β = 78.52 und γ = 82.26° and with four molecules per unit cell. There are two crystallographically independent molecules which differ somewhat in their geometry.     

Zur Deformationstheorie assoziativer Algebren auf einem Schema

Ohne Zusammenfassung