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Published on: March 20, 2017
Electrochemical Bromination of Arenes in a 200% Cell
Sara Torabi1, Mahdi Jamshidi1, Gerhard Hilt1
1Institute of Chemistry, Carl von Ossietzky University Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg, Germany.
Abstract:
Herein, we describe the investigation of electrochemical bromination of electron-rich arenes in a 200% cell. For this application, at first, the influence of an excess of supporting electrolyte (Bu4NBr) on chemical bromination was investigated. The application of >4.0 equiv of Bu4NBr proved to enhance the regioselectivity of the bromination process for O- and N-substituted arenes considerably. The linear paired electrolysis was then optimized upon these insights, and a number of electron-rich arenes could be brominated in high yields with excellent regioselectivity. The use of O2 as a sacrificial starting material in combination with 2-ethylanthraquinone as a catalyst leads to the enhanced formation of H2O2 at the cathode, resulting in current efficiencies >150% for a considerable number of examples.
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