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Continuous-flow double diazotization for the synthesis of m-difluorobenzene via Balz-Schiemann reaction

Continuous-flow double diazotization for the synthesis of m-difluorobenzene via Balz-Schiemann... m-Difluorobenzene is an important structural in many pharmaceutical agents and nature products. However, the conventional method of preparing m-difluorobenzene, which was adopts double diazotization from m-phenylenediamine, is very tricky with potential hazards associated with the strongly exothermic and thermal instability of the diazonium intermediate, and has severe coupled side reactions. Here, we report the continuous-flow methodology, which effectively addresses this series of process challenges by an extra inert solvent flow. The protocol rapidly synthesize m-Difluorobenzene with 85% total yield (the traditional method has 65% total yield). The molar ratio of hydrochloric acid used in the process deduce to 3.6 equivalent (traditional method requires 12 equivalent). Furthermore, the reaction time can be decreased from hours to within 40 s. Above all, the method has potential industrial application value.Graphical abstract[graphic not available: see fulltext] http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Flow Chemistry Springer Journals

Continuous-flow double diazotization for the synthesis of m-difluorobenzene via Balz-Schiemann reaction

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References (31)

Publisher
Springer Journals
Copyright
Copyright © Akadémiai Kiadó 2020
ISSN
2062-249X
eISSN
2063-0212
DOI
10.1007/s41981-020-00115-4
Publisher site
See Article on Publisher Site

Abstract

m-Difluorobenzene is an important structural in many pharmaceutical agents and nature products. However, the conventional method of preparing m-difluorobenzene, which was adopts double diazotization from m-phenylenediamine, is very tricky with potential hazards associated with the strongly exothermic and thermal instability of the diazonium intermediate, and has severe coupled side reactions. Here, we report the continuous-flow methodology, which effectively addresses this series of process challenges by an extra inert solvent flow. The protocol rapidly synthesize m-Difluorobenzene with 85% total yield (the traditional method has 65% total yield). The molar ratio of hydrochloric acid used in the process deduce to 3.6 equivalent (traditional method requires 12 equivalent). Furthermore, the reaction time can be decreased from hours to within 40 s. Above all, the method has potential industrial application value.Graphical abstract[graphic not available: see fulltext]

Journal

Journal of Flow Chemistry – Springer Journals

Published: Sep 15, 2020

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