Selective Electrochemical C–N Coupling via Synergetic Chemical and Electrochemical Microenvironment Regulation Strategies

Electrocatalytic C-N coupling between nitrite and benzaldehyde to form benzylamine offers a sustainable route to primary amines, yet achieving high selectivity under mild aqueous conditions remains elusive due to competing nitrite over-reduction and benzaldehyde parasitic reduction. This paper describes a synthetic microenvironment modulation method that combines chemical and electrochemical modulation to overcome these challenges. Precise adjustment of local nitrite and benzaldehyde concentrations at the electrode interface was performed to control the reaction kinetics and adsorption equilibria, effectively suppressing hydroxylamine reduction and benzaldehyde parasitic adsorption. Simultaneously, periodic current pulses were applied to a flow electrolyzer to enrich hydroxylamine within the boundary layer. Under pulsing conditions, the system achieves a benzylamine Faradaic efficiency of 65.2%, higher than the static conditions (44.7%). The electrochemical production of benzylamine was further scaled up to a 25 cm² electrolyzer, maintaining a Faradaic efficiency of 49.1%. This strategy was also extended to C-N coupling with acetaldehyde (CH₃CHO) and 2-furaldehyde, both of which exhibited favorable performance, with a FE toward amine of 69.4% and 58.6%, respectively. This work provides a generalizable framework for enhancing multistep organic electrosynthesis by combining electrochemical dynamics and chemical environment modulation, outperforming existing strategies that rely solely on catalyst design.