Coupling nitrate electrochemical reduction and nitrite oxidation of ethanol for acetamide synthesis

Abstract

Electrochemical acetamide synthesis under ambient conditions offers a sustainable route for converting waste nitrate into valuable chemicals. Conventional methods, limited to standalone reduction or oxidation processes, typically achieve low Faradaic efficiencies (<40%) and yields (<0.2 mmol h⁻¹ cm⁻²). Here, we present a tandem reaction system coupling cathodic reduction and anodic oxidation in a full-cell electrolyzer to enhance acetamide production. At the cathode, nitrate is first reduced to nitrite, which subsequently oxidizes ethanol to acetaldehyde. This acetaldehyde reacts in situ with electrogenerated ammonia to form α-aminoethanol. The intermediate is then transported to the anode, where it undergoes oxidation to yield acetamide. The reaction pathway is confirmed through proton nuclear magnetic resonance spectroscopy, revealing efficient acetamide synthesis with a yield of 7.2 ± 0.3 mmol h⁻¹ (0.45 ± 0.02 mmol h⁻¹ cm⁻²) at a cell voltage of 2.4 V. Furthermore, the strategy extends to other amides, such as formamide and butyramide, underscoring its versatility. Techno-economic analysis highlights the viability of this route, with estimated production costs competitive against conventional thermal processes.