Zur Abhängigkeit der Hydratation des CaO · Al2O3 von der Temperatur

On the Temperature Dependence of the Hydration of CaO · Al₂O₃ Using differential calorimetric analysis, ¹H-NMR spin-lattice-relaxation time measurements, and X-ray powder characterization of the hydration products it has been shown that the CaO · Al₂O₃ hydration in the range of 4 to 83°C proceeds via three different successively occurring principles.     

Notiz über die Reaktion von Methylhydrazin mit N-Cyano-azomethinen. Abhängigkeit des Reaktionsverlaufs von der Natur der Abgangsgruppe

The reaction of methylhydrazine with N-cyanoazomethines 1 containing a thioalkyl leaving group yields the 3-amino-1,2,4-triazole derivatives 2 , whereas the N-cyanoazomethines 1 containing an alkoxy leaving group give the isomeric 5-amino-1,2,4-triazoles 3. The yields are excellent and the position selectivity is high. The structures of the 1,2,4-triazole derivatives were determined with the aid of proton-coupled ¹³C-NMR. spectra.     

Zur objektiven bewertung des nachweisvermögens in der emissionsspektrographie—IV Abhängigkeit des zufallsfehlers von der grösse des messwertes

A formula describing the dependence of the statistical error from the measured quantity is derived for emission spectrographic trace analysis and confirmed experimentally in three special cases. The general importance of the lower range of such functions for the objective estimation and exhaustive utilization of the detection capacity of analytical procedures is discussed as well as their limits of applicability.     

Chlorisotopenseparation in einem heterogenen Elektrolytsystem in Abhängigkeit von Konzentration und Gegenion einer Fluoridlösung

Using the ESR method the formation of O^? and O₂^? on silica supported vanadiumphosphorus catalysts has been investigated. Studying catalysts with varying phosphorus contents it was found that the concentration of O^? and O₂^? can be related to the contents of phosphate ions. The admixture of increasing amounts of phosphorus obviously increases the reducibility of the catalysts and stabilizes the square-pyramidical coordination of V⁴⁺ ions. Comparing these results with activity and selectivity of the catalytic butene oxidation to maleic anhydride we point out that both the changed catalytic properties and the formation of oxygen radicals may be influenced by the same structural effects.     

Favorskii-Reaktion von enolisierbaren Cyclobutanonen: Abhängigkeit der Stereoselektivität von der Abgangsgruppe,der Temperatur und dem Lösungsmittel

Dependence of the Stereoselectivity on the Leaving Group, the Temperature and the Solvent in the Favorskii-Reaction of Enolisable Cyclobutanones The base-induced contraction of enolisable 2-halocyclobutanones is often not stereoselectiv. The cis/trans-isomer ratio in the cyclopropanecarboxylic acid 9 derived from 2,4-cis-substituted cyclobutanones 7 depends on the nature of the leaving group. In addition, the choice of the base, the temperature and the solvent can profoundly affect the stereoselectivity of the Favorskii-reaction. The use of the p-bromophenylsulphonyloxy group as leaving group and an inhomogenous reaction medium leads exclusively to cis-carboxylic acid 9 .     

Vier- und achtgliedrige metallhaltige Bor–Stickstoff-Heterocyclen. Bildung und Strukturen in Abhängigkeit von der Raumerfüllung der Substituenten

Four and Eight Membered Metal Containing Boron–Nitrogen-Heterocycles. Formation and Structures in Dependence on the Steric Requirement of their Substituents TripB(NRLi)₂ (Trip = 2,4,6-triisopropylphenyl, R = Me ( II a ), CH₂Me ( II b ), CHMe₂ ( II c ), CMe₃ ( II d ) reacts with dibromo(dimethyl)tin to give eight membered ( III a , III b ) and four membered metallacycles ( IV c and IV d ). If tetrahalides (GeCl₄, SnCl₄) are the reaction partners, the spiro compounds V c and VI d are obtained from II c and II d resp. The compounds are characterized by their m.s. and n.m.r. (¹H, ¹¹B, ¹³C, ¹⁹F, ¹¹⁹Sn) spectra and by elemental analyses. An X-ray structure analysis was performed for III a .