Ketal Protection of Glycerol for Selective Electrosynthesis of Glyceric Acid in Highly Alkaline Media

Abstract

ABSTRACT Electrocatalytic glycerol oxidation represents a sustainable route for glycerol valorization, yet high selectivity toward glyceric acid (GLA) remains challenging on non‐noble‐metal catalysts due to competing C─C bond cleavage and complex oxidation pathways. Herein, we introduce solketal, a ketal‐protected glycerol derivative, to steer reaction selectivity. Its rigid five‐membered ketal structure selectively exposes the primary hydroxyl group while shielding vicinal diols, thereby enforcing site‐selective oxidation and suppressing C–C scission. Using a non‐noble Cu 3 Mo 2 O 9 catalyst in 6.0 M KOH with 0.2 M solketal, the system achieves a record‐high GLA selectivity of 90.1% with a production rate of 675.45 µmol cm −2 h −1 at 1.40 V versus RHE, reaching ∼95% substrate conversion within 5 h and maintaining stable operation over 100 h. Mechanistic investigations reveal that highly alkaline conditions promote solketal deprotonation to reactive alkoxide species, weaken the C α ─H bond to accelerate dehydrogenation kinetics, and mitigate local interfacial acidification, thus stabilizing the ketal‐protected intermediate and suppressing side reactions. Furthermore, practical feasibility is demonstrated through integrated upstream solketal synthesis (90% yield, 99% purity) and downstream GLA isolation (99% purity). This work establishes a substrate‐protection strategy for steering reaction pathways, offering new insights into the selective conversion of biomass‐derived polyols into value‐added oxygenates.