Zn-Ag Nanocatalysts Enable Electrochemical Carboxylation of Carbonyl Compounds With CO2 for α-Hydroxy Carboxylic Acids Synthesis.

Current synthetic methodologies for α-hydroxy carboxylic acids are constrained by stringent reaction conditions and laborious product separation processes. To address these limitations, a Zn/Ag catalyst was prepared via a pH-regulated electrodeposition strategy in this study. By leveraging the bimetallic synergistic effect, the catalyst modulates the adsorption and activation of substrates, thereby promoting the electrochemical carboxylation of carbonyl compounds with CO2. The results showed that the Zn/Ag catalyst achieved a high yield of 83% in the conversion of acetophenone to atrolactic acid. Infrared spectroscopy analyses verified that the reaction mechanism proceeds via a Zn-Ag synergistic effect, which activates acetophenone to form a radical anion intermediate. This intermediate subsequently undergoes carboxylation with CO2, followed by an electron transfer step, to afford atrolactic acid with excellent selectivity. The catalyst facilitated the synthesis of 1.3 g of carboxylated product from acetophenone and enabled the extension of electrocarboxylation to diverse substrates, including aryl ketones, aryl aldehydes, and aliphatic ketones. This work not only provides an efficient and cost-effective route for the synthesis of α-hydroxy carboxylic acids but also validates its potential for industrial-scale application.