Continuous scalable Grignard reagent formation: Process intensification and improved selectivity in non-homogeneous packed beds of magnesium turnings

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dc.contributor.authorDeitmann, Eva Pauline
dc.contributor.refereeZiegenbalg, Dirk
dc.contributor.refereeMaskos, Michael
dc.date.accessioned2024-06-18T11:20:10Z
dc.date.available2024-06-18T11:20:10Z
dc.date.created2024
dc.date.issued2024-06-18
dc.description.abstractGrignard reagents are organometallic halides that are important in synthetic chemistry due to their ability to form carbon-carbon bonds with electrophilic substrates in the subsequent Grignard reaction. However, the formation of Grignard reagents presents several challenges, including variable incubation periods, high exothermicity, potentially excessive side product formation and its sensitivity to oxygen and moisture. Due to these challenges, Grignard reagent formation has the potential to benefit from flow chemistry and a continuous production process. The aim of this dissertation is to enhance the benefits of a continuous synthesis process for the formation of Grignard reagents and to expand the utilization to increase the process safety, improve the product quality and achieve scalability for production flexibility. To evaluate the potential of infrared spectroscopy as a process analytical technique for the identification and quantification of Grignard reagents, a literature review was conducted on the specific absorption bands of Grignard reagents and existing application examples. Based on the obtained findings, infrared spectroscopy was used in the further course of the work, e.g., to perform residence time distribution measurements. Narrow residence time distributions in non-homogeneous, randomly packed beds of non-uniform, non-spherical magnesium turnings can be obtained by decreasing the size of the magnesium turnings and increasing the packing density. The residence time distributions were also found to be significantly affected by the influence of the pump-induced flow behavior. By using oscillatory flow rates instead of pulsation-free pumps in non-reacting magnesium beds, backmixing is minimized and Bodenstein numbers were increased by 25 % for fine magnesium turnings and 70 % for coarse magnesium turnings. The pump-induced effect on the residence time distribution is also evident in the Grignard reagent selectivity. Side product formation, such as Wurtz coupling, diminishes the Grignard reagent selectivity and the product quality and therefore must be reduced. The Grignard reagent selectivity can be improved by increasing the available magnesium surface area, by choosing a packed bed tubular flow reactor instead of a semi-batch reactor and by thoughtfully selecting a suitable pump system to match the characteristics of the magnesium packing. Furthermore, by using a scale-up approach from semi-batch type syntheses to continuous lab and pilot scale syntheses, it is shown that a continuous production process has the potential to improve the selectivity of Grignard reagents in general, independent of the degree of affinity to Wurtz coupling. By using a modular reactor system at pilot scale for the synthesis of phenylmagnesium bromide, the reactor volume can be scaled to the required throughputs and necessary residence times, allowing flexibility of production without loss of selectivity. The results obtained contribute to the continuous synthesis of reactive intermediates, to the improvement of the Grignard reagent selectivity, to the targeted control of process conditions through the identification of the relevant process parameters and to the scalability of a solid/liquid reaction.
dc.identifier.doihttps://doi.org/10.18725/OPARU-53072
dc.identifier.ppn1892110954
dc.identifier.urlhttps://oparu.uni-ulm.de/handle/123456789/53148
dc.identifier.urnhttp://nbn-resolving.de/urn:nbn:de:bsz:289-oparu-53148-7
dc.language.isoen_US
dc.publisherUniversität Ulm
dc.relation.haspartE. Deitmann, M. Maskos, G. Menges-Flanagan and D. Ziegenbalg; Impact of residence time distributions in reacting magnesium packed beds on Grignard reagent formation - pump-induced flow behaviour in non-reacting magnesium beds (part 1); React. Chem. Eng., 2023, 8, 2606-2619, https://doi.org/10.1039/D3RE00190C
dc.relation.haspartE. Deitmann, M. Maskos, G. Menges-Flanagan and D. Ziegenbalg; Impact of residence time distributions in reacting magnesium packed beds on Grignard reagent formation - selectivity of Grignard reagent formation (part 2); React. Chem. Eng., 2023, 8, 2717-2728, https://doi.org/10.1039/D3RE00191A
dc.relation.haspartE. Deitmann, K. Dahms, M. Maskos, D. Ziegenbalg and G. Menges-Flanagan; Selectivity of Grignard Reagent Formation: From Semibatch to Continuous Lab and Pilot Scale; Org. Process Res. Dev., 2023, 27, 12, 2345-2354, https://doi.org/10.1021/acs.oprd.3c00305
dc.relation.haspartE. Deitmann, G. Menges-Flanagan and D. Ziegenbalg; Infrared Spectroscopy as Process Analytics to Identify and Quantify Grignard Reagents; Organometallics, 2024, 43, 3, 219-226, https://doi.org/10.1021/acs.organomet.3c00441
dc.rightsLizenz B (ohne Print-on-Demand)
dc.rights.urihttps://oparu.uni-ulm.de/xmlui/licenseB_opod_v1
dc.subjectOrganometallic reagent
dc.subjectResidence time distribution
dc.subjectProcess intensification
dc.subjectSelectivity
dc.subjectPacked bed
dc.subject.ddcDDC 540 / Chemistry & allied sciences
dc.subject.gndMagnesium
dc.subject.gndInfrarotspektroskopie
dc.subject.gndReagierende Strömung
dc.subject.lcshGrignard reagents
dc.subject.lcshInfrared spectroscopy
dc.subject.lcshFlow chemistry
dc.titleContinuous scalable Grignard reagent formation: Process intensification and improved selectivity in non-homogeneous packed beds of magnesium turnings
dc.typeDissertation
dcterms.dateAccepted2024-04-25
uulm.affiliationGeneralFakultät für Naturwissenschaften
uulm.affiliationSpecificInstitut für Chemieingenieurwesen
uulm.bibliographieuulm
uulm.categoryPublikationen
uulm.cooperationFraunhofer-Institut für Mikrotechnik und Mikrosysteme IMM
uulm.thesisGrantorFakultät für Naturwissenschaften
uulm.typeDCMIText
uulm.updateStatusURNurl_update_general

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