Faculty Publications

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Subject: search.filters.subject.Crystallization process

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    Condensation of malononitrile with salicylaldehydes and o-aminobenzaldehydes revisited: Solvent and catalyst free synthesis of 4H-chromenes and quinolines
    (Royal Society of Chemistry, 2012) Bhat, S.I.; Choudhury, A.R.; Trivedi, D.R.
    The reaction of malononitrile with salicylaldehyde under solvent and catalyst free conditions was re-investigated using mechanochemical mixing, thermal heating and a direct crystallization process. The resulting condensation product by all three types of molecular activation, was found to be (2-amino-3-cyano-4H-chromene-4-yl)malononitrile, which is not the previously reported benzofuran-2-carbonitrile. The structure of the resulting chromene derivative was confirmed by FT-IR, MS, 1H, 13C NMR and single crystal and powder X-ray diffraction. The reaction pathway under neat conditions (mechanochemical mixing) at ambient temperature was monitored by IR spectral measurements. The versatility of the current green protocol was examined through the reaction of eleven derivatives of o-hydroxybenzaldehyde with malononitrile to obtain 2-amino-3-cyano-4H-chromene derivatives. In addition, malononitrile was further reacted with o-aminobenzaldehydes under neat conditions to yield quinoline derivatives. © 2012 The Royal Society of Chemistry.
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    Coupled computational fluid dynamics-discrete element method simulations of a pilot-scale batch crystallizer
    (American Chemical Society service@acs.org, 2015) Ali, B.; Börner, M.; Peglow, M.; Janiga, G.; Seidel-Morgenstern, A.; Thévenin, D.
    Computational fluid dynamics (CFD) coupled with the discrete element method (DEM) has been used to investigate numerically crystal dynamics in an existing pilot-scale batch crystallizer. The CFD-DEM combination provides a detailed description of crystal dynamics considering a four-way coupling. In a previous analysis,1 CFD had been coupled with a discrete phase model (DPM) using a simple one-way coupling. The corresponding predictions are then compared with those obtained through four-way coupling considering KH2PO4 crystals in water. From the CFD-DEM simulation, it is possible to investigate quantitatively the driving force controlling crystal growth and the interaction of crystals with reactor walls, baffles, and impellers. This delivers essential data for process improvement. Different seeding procedures were also compared. The seed crystals have been injected either within the complete liquid volume or, as in the experiments, through a funnel. By varying the most important crystallization process parameters, we found optimal conditions for a liquid phase volume in the crystallizer of 24 L, for injection through a funnel above the baffle, and for an initial seed crystal size of 0.5 mm. © 2014 American Chemical Society.