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Continuous Flow Synthesis of Azoxybenzenes by Reductive Dimerization of Nitrosobenzenes with Gel‐Bound Catalysts
Author(s) -
Schmiegel Carsten J.,
Berg Patrik,
Obst Franziska,
Schoch Roland,
Appelhans Dietmar,
Kuckling Dirk
Publication year - 2021
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.202100006
Subject(s) - chemistry , yield (engineering) , catalysis , flow chemistry , microfluidics , continuous flow , combinatorial chemistry , microreactor , proton nmr , turnover number , organic chemistry , nanotechnology , thermodynamics , materials science , physics , mechanics
In the search for a new synthetic pathway for azoxybenzenes with different substitution patterns, an approach using a microfluidic reactor with gel‐bound proline organocatalysts under continuous flow is presented. Herein the formation of differently substituted azoxybezenes by reductive dimerization of nitrosobenzenes within minutes at mild conditions in good to almost quantitative yields is described. The conversion within the microfluidic reactor is analyzed and used for optimizing and validating different parameters. The effects of the different functionalities on conversion, yield, and reaction times are analyzed in detail by NMR. The applicability of this reductive dimerization is demonstrated for a wide range of differently substituted nitrosobenzenes. The effects of these different functionalities on the structure of the obtained azoxyarenes are analyzed in detail by NMR and single‐crystal X‐ray diffraction. Based on these results, the turnover number and the turnover frequency were determined.