Green Electrosynthesis of Hydroxylamines via CuS Suppressing N─O Bond Cleavage

Organic hydroxylamines, pivotal intermediates in pharmaceutical and polymer chemistry, face persistent challenges in selective synthesis. Its main difficulty lies in the strong repulsion between the lone pair electrons on the N and O atoms, which makes their N─O bond easy to break, leading to a over-reduction to amine compounds. Here, we present a green electrocatalytic strategy for the first time that converts oximes to hydroxylamines over CuS. Specially, N-benzylhydroxylamine was achieved with 95% conversion and 80% selectivity from benzaldoxime at -0.9 V versus reversible hydrogen electrode. Mechanistic investigations reveal that CuS can optimize the adsorption energy of the reaction intermediates, making the N─O bond more difficult to cleave during the electrocatalytic hydrogenation, thus leading to a high selectivity formation of hydroxylamines. This methodology is successfully extended to other hydroxylamines and further enables the unprecedented synthesis of organic hydroxylamines from nitric oxide gas. Our work establishes a sustainable electrosynthetic platform for hydroxylamines synthesis without organic solvents and additional reduction agents, providing new insights for modern green chemical synthesis.