Sustainable Electrochemical Synthesis of Organic Hydrazines via Zn2+/Zn0-Mediated Reduction of N-Nitroso Compounds.

The reduction of N-nitroso compounds offers a promising route to synthesize valuable organic hydrazines. However, conventional methods often rely on costly noble metals, require harsh reaction conditions, and impose significant environmental burdens, limiting their industrial scalability. To address these challenges, we introduce a sustainable Zn2+/Zn0-mediated electrochemical strategy for the efficient reduction of representative N-nitroso compounds under mild conditions. This approach eliminates the need for both noble-metal catalysts and stoichiometric chemical reductants. Applied across four representative substrates, the method affords the corresponding hydrazines and derivatives in high yields (78.8-93.9%). Crucially, the reaction exhibits feasible scalability: it successfully transitions from H-type cells to flow-cell reactors for stable multicycle processing, and further scales to plate-and-frame electrolyzers with electrode areas up to 91 cm2, all while maintaining low operational cell voltages (3-4 V). The process demonstrates inherent sustainability features, including the recyclability of the major over-reduction byproduct back to the precursor and the reusability of the electrolyte solution over multiple cycles, pointing toward potential closed-loop material utilization. Mechanistic studies indicate that selective N-NO bond cleavage occurs predominantly through a Zn2+/Zn0-mediated electrochemical-chemical (EC) pathway, rather than direct cathodic reduction.