Plasma Electrochemistry for Carbon–Carbon Bond Formation via Pinacol Coupling

Abstract

The formation of carbon-carbon bonds by pinacol coupling of aldehydes and ketones requires a large negative reduction potential, often realized with a stoichiometric reducing reagent. Here, we use solvated electrons generated via a plasmaliquid process. Parametric studies with methyl-4-formylbenzoate reveal that selectivity over the competing reduction to the alcohol requires careful control over mass transport. The generality is demonstrated with benzaldehydes, benzyl ketones, and furfural. A reaction-diffusion model explains the observed kinetics, and ab initio calculations provide insight into the mechanism. This study opens the possibility of a metal-free, electrically-powered, sustainable method for reductive organic reactions.

Morphology Engineering toward Highly Efficient NiO Nanocatalysts for Oxygen-Promoted Hydrogen Production from Formaldehyde Solution

“…However, further increases in NaOH concentration resulted in the inhibition of the H 2 evolution reaction. We propose that this phenomenon arises from the tendency of aldehydes to undergo the Cannizzaro reaction (formation of alcohols and carboxylates) under high NaOH conditions, which competes with the catalytic H 2 production pathway. Additionally, the HCHO concentration significantly influences the rate of H 2 production (the specific experimental conditions are shown in Figure S5), and an optimal concentration of 1.0 M was identified thereof.…”

Plasma-Enabled Graphene Quantum Dot Hydrogel–Magnesium Composites as Bioactive Scaffolds for In Vivo Bone Defect Repair

“…Although there is no direct plasma penetration deep inside the hydrogels, the plasma interaction with the liquid can produce solvated electrons that are highly reactive. A recent report has shown that these solvated electrons can promote carbon–carbon bond formation via pinacol coupling of aldehydes and ketones . Therefore, it is expected that the plasma-electrified solution coupled to the presence of NGQDs in the hydrogels can promote the cross-linking reaction within the composites.…”

Selective Electrochemical Modification and Degradation of Polymers

“…Electrochemical methodologies are experiencing a renaissance in small‐molecule synthetic chemistry. Efficiently forging covalent bonds by electrochemically adding or removing electrons from a substrate is a straightforward approach to synthetic chemistry [1–3] . Emerging electrochemical techniques have recently achieved chemo‐ and regio‐selective transformations with high atom economy [4,5] .…”

“…Efficiently forging covalent bonds by electrochemically adding or removing electrons from a substrate is a straightforward approach to synthetic chemistry. [1][2][3] Emerging electrochemical techniques have recently achieved chemo-and regioselective transformations with high atom economy. [4,5] The simplicity, selectivity, and scalability of electrochemistry provide a 'green methodology' to modify small molecules.…”