Selective Enzymatic Synthesis of Glucose Fatty Acid Esters in a Choline Chloride-Glucose Reactive Deep Eutectic...

Sugar fatty acid esters are bio-based surfactants, but their enzymatic synthesis is limited by poor substrate compatibility in conventional media. In this study, a choline chloride (ChCl)-glucose reactive deep eutectic solvent (RDES) was investigated for lipase-catalyzed transesterification of glucose with vinyl laurate. In this system, glucose, choline, and water compete for a common acyl-enzyme intermediate, so product distribution is governed primarily by kinetic competition rather than thermodynamic equilibrium. By systematically controlling water content and the ChCl:glucose ratio, the effects of RDES composition on this pathway competition and product distribution were evaluated. Controlled adjustment of these parameters suppressed hydrolysis and competing choline-derived ester formation, thereby promoting the selective formation of glucose monolaurate (GML). Under optimized conditions, a GML yield of approximately 46% was achieved, corresponding to a volumetric productivity of 12 g L^-1 h^-1, which significantly exceeded that obtained in conventional organic solvent-based systems. The synthesized GML was purified and structurally confirmed using high-performance liquid chromatography, mass spectrometry, and ¹H and ¹³C nuclear magnetic resonance. The applicability of the optimized RDES system was further demonstrated using vinyl esters with varying acyl chain lengths, highlighting its broader potential for selective enzymatic synthesis of sugar fatty-acid esters.