Filters

2017 - 20202

More filters

2019 - 201912020 - 20211
Reset filters

Settings

Subject: Green chemistry × WGL Institute: IPHT ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Novel Application of Polymer Networks Carrying Tertiary Amines as a Catalyst Inside Microflow Reactors Used for Knoevenagel Reactions
    (Weinheim : Wiley-VCH Verl., 2020) Berg, Patrik; Obst, Franziska; Simon, David; Richter, Andreas; Appelhans, Dietmar; Kuckling, Dirk
    A novel application is described for utilizing hydrogel dots as organocatalyst carriers inside microfluidic reactors. Tertiary amines were covalently immobilized in the hydrogel dots. Due to the diffusion of reactants within the swollen hydrogel dots, the accessible amount of catalysts inside a microfluidic reactor chamber can be increased compared to the accessible amount of surface-bound catalysts. To perform fast Knoevenagel reactions, important flow parameters had to be validated to optimize the reactor performance while keeping the dimensions of the reactor chamber constant; e.g. the height of the hydrogel dots had to be adjusted to the invariable dimensions of the reactor chamber, or an adjustment of organocatalysts in the hydrogel dots had to be validated to achieve the highest conversion rate during a certain residence time. To characterize the conversion, nuclear magnetic resonance (NMR) and UV/Vis-spectroscopy were utilized as an offline and online method, respectively. With suitable hydrogel dots, the influence of different flow parameters (e.g., operating flow rate and reactant concentration) on the selected model reactions in the microfluidic reactor was investigated. Finally, a variety of reactants were screened with the optimized flow parameters. With these results, the turnover frequency was determined for the Knoevenagel reactions in a microfluidic reactor, and the results were compared with published data that were determined by other synthetic approaches. © 2020 The Authors published by Wiley-VCH GmbH
  • Thumbnail Image
    Item
    Chemical and electrochemical synthesis of platinum black
    (London : Nature Publishing Group, 2017) Stanca, S.E.; Hänschke, F.; Ihring, A.; Zieger, G.; Dellith, J.; Kessler, E.; Meyer, H.-G.
    We present electrochemical and chemical synthesis of platinum black at room temperature in aqueous and non-aqueous media. X-ray analysis established the purity and crystalline nature. The electron micrographs indicate that the nanostructures consist of platinum crystals that interconnect to form porous assemblies. Additionally, the electron micrographs of the platinum black thin layer, which was electrochemically deposited on different metallic and semiconductive substrates (aluminium, platinum, silver, gold, tin-cooper alloy, indium-tin-oxide, stainless steel, and copper), indicate that the substrate influences its porous features but not its absorbance characteristics. The platinum black exhibited a broad absorbance and low reflectance in the ultraviolet, visible, and infrared regions. These characteristics make this material suitable for use as a high-temperature resistant absorber layer for the fabrication of microelectronics.