Electrosynthesis of nitriles from primary alcohols and ammonia on Ni catalysts

Despite increasing interest in electrocatalytic refineries for producing value-added chemicals, heterogeneous nitrile electrosynthesis from alcohols is still in the initial stages of investigation. Herein, we report the direct electrosynthesis of nitriles from primary alcohols and ammonia, with a simple nickel catalyst under benign conditions in aqueous electrolytes. The highest benzonitrile faradaic efficiency of 62.9% and a formation rate of 93.2 mmol m-2cat h-1 were achieved at room temperature. The reaction proceeds via a dehydrogenation-imination-dehydrogenation sequence, with the rate-determining step likely involving the cleavage of the alpha-carbon C-H bond of the alcohol. Based on electrochemical and in situ Raman analyses, we propose that the in situ formed Ni2+/Ni3+ redox species serves as the active site for converting alcohol to nitrile, while Ni2+ also exhibits capability for the oxidation of imine. Various aromatic, aliphatic and heterocyclic primary alcohols were transformed into the corresponding nitriles, exhibiting the broad feasibility of our strategy. This study offers a cost-effective catalyst-based electrocatalytic system for the synthesis of high-value nitriles under mild conditions.