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Updated: May 16, 2026
07:06
A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis
Published on: February 16, 2020
Micro/milliflow processing with selective catalyst microwave heating in the Cu-catalyzed Ullmann etherification
Faysal Benaskar1, Narendra G Patil, Evgeny V Rebrov
1Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Den Dolech 2, 5600 MB Eindhoven, The Netherlands.
Chemsuschem
|November 30, 2012
Summary
This study combined microwave heating and microflow technology for Ullmann-type C-O coupling. Supported copper nanocatalysts in a micro-fixed-bed reactor achieved high yields (up to 80%) with enhanced activity and stability.
Area of Science:
- Organic Chemistry
- Chemical Engineering
- Materials Science
Background:
- Ullmann-type C-O coupling is crucial for synthesizing diaryl ethers.
- Traditional heating methods can be inefficient and lead to side reactions.
- Microwave (MW) irradiation and microflow reactors offer potential for process intensification.
Purpose of the Study:
- To investigate the combined microwave and microflow process for Ullmann-type C-O coupling.
- To evaluate the performance of supported copper nanocatalysts in a micro-fixed-bed reactor (μ-FBR).
- To explore novel process windows for organic synthesis by optimizing reaction parameters.
Main Methods:
- A multisegmented μ-FBR packed with Cu/TiO(2) and CuZn/TiO(2) coated beads was used.
- Selective microwave absorption by the supported Cu nanocatalyst was utilized.
- Temperature was monitored using fiber-optic probes, enabling isothermal operation.
- Solvent and reaction mixture properties were adjusted for optimal MW power transfer.
- Catalyst synthesis involved sol-gel, deposition, and impregnation methods.
Main Results:
- High yields (up to 80%) were achieved in the combined MW and microflow process.
- The μ-FBR with supported Cu nanocatalysts showed increased activity compared to oil-bath heating.
- The reactor operated isothermally at 20 W due to simultaneous MW power and temperature control.
- CuZn/TiO(2) catalyst demonstrated enhanced activity due to stable Cu(0) species.
- No significant catalyst deactivation was observed over the experimental survey.
Conclusions:
- The combined microwave and microflow process offers an efficient and selective route for Ullmann-type C-O coupling.
- Supported copper nanocatalysts, particularly CuZn/TiO(2), are effective for this transformation.
- This study presents the first extensive survey of parameters for combining microprocess and MW technology, establishing novel process windows for organic synthesis.
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