Inhaltszusammenfassung

Organomagnesium halides, also known as Grignard reagents, are important intermediates for the formation of new carbon–carbon bonds in synthetic chemistry. In the pharmacy sector, they became especially useful for the formation of active pharmaceutical ingredients, e.g. pain-reliever ibuprofen and breast cancer drug tamoxifen.1 Grignard reagents originate from an exothermic reaction of metallic magnesium (mostly powder or turnings) and a halide in a water free ethereal solvent. Side product fo...Organomagnesium halides, also known as Grignard reagents, are important intermediates for the formation of new carbon–carbon bonds in synthetic chemistry. In the pharmacy sector, they became especially useful for the formation of active pharmaceutical ingredients, e.g. pain-reliever ibuprofen and breast cancer drug tamoxifen.1 Grignard reagents originate from an exothermic reaction of metallic magnesium (mostly powder or turnings) and a halide in a water free ethereal solvent. Side product formation due to the Wurtz coupling reaction can occur, in which a Grignard reagent molecule (product) reacts with a halide molecule (educt), diminishing the yield of the Grignard reagent.2 Therefore, reducing the contact between the formed Grignard reagent and the halide educt would prevent Wurtz coupling. Consequently, residence time distributions (RTDs) in tubular flow reactors equipped with a packed bed of magnesium turnings will have an impact on product distribution. To minimize the contact between the halide educt and the Grignard reagent, a plug-flow like behaviour is favourable, ideally having a constant velocity across the cross-section of the tube and no backmixing, resulting in a narrow residence time distribution. The residence time distribution of chemical reactors depends on the flow and mixing conditions and is a long-known tool of reactor development to estimate the hydrodynamic characteristics of a reactor. The data obtained can also be used to make statements about the average residence time of a volume element within the investigated system, and by applying a model, the dimensionless Bodenstein number Bo can be estimated. » weiterlesen» einklappen

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DDC Sachgruppe:
Chemie