C≡N triple bond cleavage via transmembrane hydrogenation

Renewable-energy-powered electrosynthesis is an emerging green alternative to thermochemical routes. Against this backdrop, acetonitrile valorization is an important target because it is industrially produced in excess. Here we developed a catalytic system that converts acetonitrile into acetaldehyde and NH3 using an H-permeable Pd membrane reactor. In this system, H is abstracted from water in an aqueous electrolyte and transferred across the Pd membrane and is used to hydrogenate acetonitrile with up to 60% faradic efficiency (FE) for NH3 generation. We also constructed a unique infrared (IR) spectroelectrochemical cell that enabled us to probe the reaction as it occurred. This helped us deduce that the reaction proceeded through an imine hydrolysis pathway. Finally, we extended the scope of this system to four additional nitrile reactants. This work establishes a new electrochemical route to nitrile hydrogenation and opens up promising avenues in electrosynthetic technologies.