Continuous-flow transfer hydrogenation of benzonitrile using formate as a safe and sustainable source of hydrogen

The continuous catalytic transfer hydrogenation of benzonitrile to benzylamine is demonstrated using a palladium on carbon catalyst with triethylammonium formate as reducing agent. Solvent choice was critical in overcoming rapid catalyst deactivation. A 15-fold increase in catalyst productivity was observed in flow compared to batch, which was achieved using an ethanol-water solvent in combination with intermittent catalyst regeneration by washing with water.