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Roughness-Dependent Electro-Reductive Coupling of Nitrobenzenes and Aldehydes on Copper Electrodes
Yinjian Zheng1, Zhiyuan Wang1, Peng Chen1
1College of Chemistry and Materials Science, and Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications, Jinan University, No. 601, Huangpu Avenue West, Guangzhou, 510632, P. R. China.
Chemsuschem
|March 29, 2023
Summary
Surface roughness of copper electrodes controls product selectivity in electro-reductive coupling of nitro and carbonyl compounds. Tailored roughness switches synthesis between nitrones and imines, offering a new route for electrochemical synthesis.
Area of Science:
- Electrochemistry
- Organic Synthesis
- Materials Science
Background:
- Electro-reductive coupling of nitro and carbonyl compounds offers an eco-friendly route to nitrones and imines.
- Achieving high selectivity in these reactions remains a significant challenge.
- Controlling the reduction of nitroarenes to specific intermediates (hydroxylamines or amines) is key.
Purpose of the Study:
- To investigate the effect of copper electrode surface roughness on the selectivity of electro-reductive coupling reactions.
- To demonstrate a method for controlling product distribution (nitrones vs. imines) by tailoring electrode surface properties.
- To establish surface/interfacial engineering as a viable strategy for optimizing electrochemical synthesis.
Main Methods:
- Electrochemical reduction using copper electrodes with varying surface roughness.
- Systematic variation of electrode surface topography through electrochemical roughening.
- Analysis of reaction products using analytical techniques to determine selectivity.
- Testing the developed method across a range of nitroarene and carbonyl compound substrates.
Main Results:
- Electrode surface roughness was identified as a critical factor determining product selectivity.
- Smoother Cu electrodes favored nitrone formation (98% selectivity with nitrobenzene and furfural).
- Roughened Cu electrodes (electrochemically treated with I-) favored imine formation (80% selectivity with nitrobenzene and furfural).
- The observed roughness-dependent selectivity was consistent across a broad scope of substrates.
Conclusions:
- Surface roughness of Cu electrodes can precisely control the selectivity between nitrones and imines in electro-reductive coupling.
- Tailoring the Cu^I/Cu^0 interface through surface engineering enables controllable reduction pathways.
- This approach offers a promising strategy for developing selective and efficient electrochemical synthesis methods.
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