Wenn die Rührgeschwindigkeit die Produktverteilung bestimmt: Selektivität mischungsmaskierter Reaktionen

Many chemical reactions are so fast relative to mixing that significant conversion takes place before homogenization down to the molecular scale is reached. In such cases, the bond‐breaking and bond‐forming events mainly occur in regions where concentrations gradients are still present. Consequently the rate of mixing can have a pronounced effect on the kinetics and the product distribution in competitive chemical reactions. This review gives an account of such mixing‐sensitive single‐phase liquid‐liquid chemical reactions where all reactants and products are soluble, because a better understanding of the coupling between mixing and chemical reaction is needed to optimize the product distribution by choosing the appropriate reactor geometry and mixing conditions. Additionally these reactions have the potential to be employed as an exploratory microprobe to investigate the local flow characteristics or the mixing process at the molecular level and to evaluate the mechanism of chemical reactions.     

Über die Darstellung und die Eigenschaften von σ-Organylwolframpentachloriden

Tungsten hexachloride reacts with dimethyl zinc or diphenyl zinc forming green methyl or phenyl tungsten pentachloride. However, tungsten hexachloride is reduced to tungsten tetrachloride on addition of zinc dialkyls with longer alkyl groups. Furthermore, alkyl tungsten pentachlorides can be prepared from tungsten hexachloride and tin tetraalkyls or boron trialkyls.     

Konversionsmaterialien für die Energiespeicherung

Conversion materials seem to be the only option at the moment to achieve considerably higher gravimetric and volumetric storage capacities of H storage materials and batteries. Although some technical problems exist with the current materials they are a rewarding field for research and development, with the perspective to achieve significant progress in the development of energy storage systems. It has been shown that new approaches for synthesis of complex nanostructures with a high functionality may open the door to this exciting new class of energy storage materials.