Highly Efficient One-pot Electrosynthesis of Oxime Ethers from NOx over Ultrafine MgO Nanoparticles Derived from...

Oxime ethers are attractive compounds in medicinal scaffolds due to the biological and pharmaceutical properties, however, the crucial and widespread step of industrial oxime formation using explosive hydroxylamine (NH₂OH) is insecure and troublesome. Herein, we present a convenient method of oxime ether synthesis in a one-pot tandem electrochemical system using magnesium based metal-organic framework-derived magnesium oxide anchoring in self-supporting carbon nanofiber membrane catalyst (MgO-SCM), the in situ produced NH₂OH from nitrogen oxides electrocatalytic reduction coupled with aldehyde to produce 4-cyanobenzaldoxime with a selectivity of 93 % and Faraday efficiency up to 65.1 %, which further reacted with benzyl bromide to directly give oxime ether precipitate with a purity of 97 % by convenient filtering separation. The high efficiency was attributed to the ultrafine MgO nanoparticles in MgO-SCM, effectively inhibiting hydrogen evolution reaction and accelerating the production of NH₂OH, which rapidly attacked carbonyl of aldehydes to form oximes, but hardly crossed the hydrogenation barrier of forming amines, thus leading to a high yield of oxime ether when coupling benzyl bromide nucleophilic reaction. This work highlights the importance of kinetic control in complex electrosynthetic organonitrogen system and demonstrates a green and safe alternative method for synthesis of organic nitrogen drug molecules.