Electrophilic Bromination in Flow: A Safe and Sustainable Alternative to the Use of Molecular Bromine in Batch

Bromination reactions are crucial in today&#8217;s chemical industry since the versatility of the formed organobromides makes them suitable building blocks for numerous syntheses. However, the use of the toxic and highly reactive molecular bromine (Br<sub>2</sub>) makes these bromina...

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Bibliographic Details
Main Authors: Reinout Van Kerrebroeck, Pieter Naert, Thomas S. A. Heugebaert, Matthias D’hooghe, Christian V. Stevens
Format: Article
Language:English
Published: MDPI AG 2019-06-01
Series:Molecules
Subjects:
Online Access:https://www.mdpi.com/1420-3049/24/11/2116
Description
Summary:Bromination reactions are crucial in today&#8217;s chemical industry since the versatility of the formed organobromides makes them suitable building blocks for numerous syntheses. However, the use of the toxic and highly reactive molecular bromine (Br<sub>2</sub>) makes these brominations very challenging and hazardous. We describe here a safe and straightforward protocol for bromination in continuous flow. The hazardous Br<sub>2</sub> or KOBr is generated in situ by reacting an oxidant (NaOCl) with HBr or KBr, respectively, which is directly coupled to the bromination reaction and a quench of residual bromine. This protocol was demonstrated by polybrominating both alkenes and aromatic substrates in a wide variety of solvents, with yields ranging from 78% to 99%. The protocol can easily be adapted for the bromination of other substrates in an academic and industrial environment.
ISSN:1420-3049