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Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds
Published on: October 18, 2018
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Molecular Processes That Control Organic Electrosynthesis in Near-Electrode Microenvironments
Ricardo Mathison1, Rasha Atwi2, Hannah B McConnell1
1Department of Chemical and Biomolecular Engineering, New York University, Brooklyn, New York 11201, United States.
Journal of the American Chemical Society
|January 27, 2025
Summary
Industrial electrosynthesis of adiponitrile (ADN) from acrylonitrile (AN) is optimized by understanding the electrical double layer (EDL). Tetraalkylammonium ions in the EDL enhance AN concentration and selectivity, guiding future electro-organic reaction design.
Area of Science:
- Electrochemistry
- Organic Synthesis
- Chemical Engineering
Background:
- Industrial electrosynthesis offers a greener alternative to traditional chemical manufacturing, utilizing renewable electricity.
- Adiponitrile (ADN) synthesis via acrylonitrile (AN) electrohydrodimerization is a key industrial process, but its mechanism requires further elucidation.
- Current understanding of near-electrode molecular processes in AN electrohydrodimerization is limited.
Purpose of the Study:
- To investigate the molecular mechanisms and interfacial phenomena governing acrylonitrile (AN) electrohydrodimerization.
- To elucidate the role of the electrical double layer (EDL) composition in enhancing reaction selectivity and efficiency.
- To provide experimental evidence for mechanistic hypotheses and guide the design of electro-organic reactions.
Main Methods:
- In situ Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) spectroscopy to study EDL composition and molecular interactions.
- Kinetic isotope effect studies to determine rate-limiting steps for propionitrile (PN) and ADN formation.
- Electron Paramagnetic Resonance (EPR) spectroscopy to detect and characterize reaction intermediates, such as free radicals.
Main Results:
- Tetraalkylammonium ions accumulate in the EDL, creating a hydrophobic microenvironment that concentrates AN and excludes water.
- Propionitrile (PN) formation is identified as proton transfer rate-limited, while ADN formation is likely not.
- Free radicals are detected during AN electroreduction, indicating that PN radical coupling occurs in the bulk electrolyte.
Conclusions:
- The composition of the EDL significantly influences selectivity and efficiency in organic electrosynthesis.
- Controlling EDL properties is crucial for optimizing ADN synthesis and other electro-organic processes.
- Findings provide fundamental engineering guidance for designing advanced electrolytes and electrode interfaces for industrial electrosynthesis.
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