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Subject: search.filters.subject.540Subject: search.filters.subject.620Start date: 2020Institute: search.filters.UBSInstitut.Institut für Technische Thermodynamik und Thermische Verfahrenstechnik

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    Calculation of pure substance and mixture viscosities using PCP-SAFT and entropy scaling
    (Stuttgart : Universität Stuttgart, Institut für Technische Thermodynamik und Thermische Verfahrenstechnik, 2020) Lötgering-Lin, Oliver; Gross, Joachim (Prof. Dr.-Ing.)
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    Influence of ionic liquid film thickness and flow rate on macrocyclization efficiency and selectivity in supported ionic liquid‐liquid phase catalysis
    (2024) Högler, Marc; Kobayashi, Takeshi; Kraus, Hamzeh; Atwi, Boshra; Buchmeiser, Michael R.; Fyta, Maria; Hansen, Niels
    Supported ionic‐liquid phase (SILP) technology in a biphasic setting with n ‐heptane as the transport phase was applied to the Ru‐alkylidene‐N‐heterocyclic carbene (NHC) catalyzed macrocyclization of α , ω ‐dienes to elucidate the effect of ionic liquid (IL)‐film thickness, flow rate as well as substrate and product concentration on macrocyclization efficiency, and Z ‐selectivity. To understand the molecular‐level behavior of the substrates and products at the n ‐heptane/IL interphase, atomistic molecular dynamics simulations were conducted and correlated with experimental observations. The thickness of the IL layer strongly influences the Z/E ratio of the products in that a thin IL layer favors higher Z/E ratios by confining the catalyst between the pore wall and the liquid‐liquid interphase whereas a thick IL layer favors formation of the E ‐product and Ru‐hydride catalyzed isomerization reactions. Also, macrocyclization efficiency, expressed by the ratio of oligomers/macromonocycle (O/MMC), is influenced both by the flow rate and the thickness of the IL layer.
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    Biocatalytic stereocontrolled head-to-tail cyclizations of unbiased terpenes as a tool in chemoenzymatic synthesis
    (2024) Schneider, Andreas; Lystbæk, Thomas B.; Markthaler, Daniel; Hansen, Niels; Hauer, Bernhard
    Terpene synthesis stands at the forefront of modern synthetic chemistry and represents the state-of-the-art in the chemist’s toolbox. Notwithstanding, these endeavors are inherently tied to the current availability of natural cyclic building blocks. Addressing this limitation, the stereocontrolled cyclization of abundant unbiased linear terpenes emerges as a valuable tool, which is still difficult to achieve with chemical catalysts. In this study, we showcase the remarkable capabilities of squalene-hopene cyclases (SHCs) in the chemoenzymatic synthesis of head-to-tail-fused terpenes. By combining engineered SHCs and a practical reaction setup, we generate ten chiral scaffolds with >99% ee and de , at up to decagram scale. Our mechanistic insights suggest how cyclodextrin encapsulation of terpenes may influence the performance of the membrane-bound enzyme. Moreover, we transform the chiral templates to valuable (mero)-terpenes using interdisciplinary synthetic methods, including a catalytic ring-contraction of enol-ethers facilitated by cooperative iodine/lipase catalysis.