Solid electrolyte interphase (SEI) triggered electrochemical hydrogenation of nitrobenzene with an undivided cell

The hydrogenation of nitrobenzene is a vital route to obtain industrially valuable aniline. Strategies have been developed to accomplish this transformation sustainably and efficiently corresponding to the green requirement of modern chemistry. The study explores an electrochemical protocol to obtain the expected product in an undivided cell without loading heterogeneous catalysts on electrodes. An additive, tripyrolidinophosphine (TPPA), forming a solid electrolyte interphase (SEI), inspired by a lithium battery technology, triggers this reaction that would otherwise not occur in a LiBr/THF system. δ-valerolactam (2-piperidone), a unique hydrogen donor, provides the H species and elevates the aniline selectivity to 75.48%. Two reductive paths are discovered existing in this system where aniline is produced from both the direct hydrogenation of phenylhydroxylamine and the indirect hydrolysis of azobenzene. Gram scale reactions are performed under batch and flow conditions, respectively, to make this protocol applicable in practice.