Highly Selective Electrosynthesis of Glycine from Glyoxylic Acid and Nitrate via Stabilizing the NH2OH Intermediates.

Electrochemical C-N coupling reactions have emerged as an important strategy for synthesizing value-added organic compounds under ambient environment, among which glycine is of practical importance for various biological activities and pharmaceutical synthesis. However, such synthesis suffers from limited selectivity due to the complex reaction pathways. In this study, we report the highly selective synthesis of glycine from the electrocatalytic co-reduction of nitrate and glyoxylic acid via stabilizing the intermediates of NH2OH and optimizing the absorption of glyoxylic acid on copper-based model catalysts. Theoretical calculations and operando measurements indicate that CuSn alloys promote the generation of NH2OH and optimize the absorption of glyoxylic acid, thereby facilitating the precise coupling of C-N groups to synthesize glycine. Consequently, the CuSn electrocatalyst delivers an excellent performance for the co-reduction to generate glycine with a maximum Faradaic efficiency and selectivity of 78.69% and 99.32%, respectively. Moreover, the CuSn catalyst enables the production of 0.73 g of glycine with a conversion rate of 100%, respectively, in large-scale synthesis. Techno-economic analysis reveals that the total cost for the proposed method is 1158.88 $ ton-1, 1.78-fold lower than the commercial price (2060.44 $ ton-1), suggesting that the electrosynthesis of glycine in our system is a feasible and profitable route.