Electrosynthesis of nitriles from primary alcohols and ammonia on Ni catalyst

Abstract

Despite increasing interest on the electrocatalytic refinery to produce value-added chemicals, heterogeneous nitrile electrosynthesis from alcohols is still in the initial stage of investigation. Here, 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 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 α-carbon C-H bond of the alcohol. Based on the 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 to the corresponding nitriles, exhibiting broad feasibility of our strategy. This study offers a cheap catalyst based electrocatalytic system for the synthesis of high-value nitriles under mild conditions.