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Potential-mediated enol-keto equilibrium in phenol electro-hydrogenation on platinum
Qing-Yang Liu1, Chong-Hui Jiang1, Zhen Yao2
1Department of Chemistry and Guangdong Provincial Key Laboratory of Catalytic Chemistry, Southern University of Science and Technology, Shenzhen, China.
Electrocatalytic hydrogenation of phenol selectively forms cyclohexanone by shifting the enol-keto equilibrium via cathodic potentials. This surface-mediated charge transfer and stabilization of cyclohexanone prevents further hydrogenation, controlling product selectivity.
Area of Science:
- Catalysis
- Physical Chemistry
- Computational Chemistry
Background:
- Phenol electrocatalytic hydrogenation (ECH) selectivity is crucial.
- Understanding cyclohexanone formation mechanisms under cathodic potentials is limited.
Purpose of the Study:
- Investigate the mechanistic basis for cyclohexanone selectivity in phenol ECH.
- Elucidate the role of cathodic potentials in product distribution.
Main Methods:
- Ab initio molecular dynamics simulations.
- Explicit solvation modeling.
- Electrode potential control.
Main Results:
- Cathodic polarization shifts enol-keto equilibrium towards the keto form via surface charge transfer.
- This promotes aromatic ring hydrogenation to cyclohexanone.
- The negatively charged surface stabilizes cyclohexanone, suppressing further hydrogenation.
Conclusions:
- Potential-controlled tautomerization is the key step influencing cyclohexanone selectivity in phenol ECH.
- Provides a mechanistic explanation for observed product distributions.
- Offers insights for designing selective electrocatalytic hydrogenation processes.
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