Catalyst-Free Cyanation of Arenes by Acetonitrile in a Plasma-Liquid Microreactor.

A catalyst-free direct C-H cyanation of arenes was performed in continuous flow by treating aromatic substrates in acetonitrile with an argon plasma in a gas-liquid microreactor under ambient conditions. The reactivity of the different radicals generated through plasma activation of acetonitrile was probed using benzene as a model substrate, producing benzonitrile in a 25% yield. Mechanistic insights derived from kinetic modeling and isotopic labeling experiments enabled the proposal of a reaction pathway accounting for the formation of the main nitrile products. Expanding the substrate scope demonstrated consistent nitrile formation aligned with the mechanistic hypothesis. This catalyst-free direct C-H cyanation of arenes using an accessible and low-toxicity nitrile source highlights the promising role of plasma activation as an alternative tool for organic transformations.