Performance optimization and mechanism of urea diacetic acid synthesis from glycine catalyzed by DES

In this study, a green catalytic strategy based on a deep eutectic solvents (DES) was developed for the efficient synthesis of urea diacetic acid. The effect of the formation of DES with different metal salts (ZnCl 2 , FeCl 3 , CuCl 2 , ZnBr 2 ) was systematically evaluated by combining experimental analysis and molecular thermodynamic simulation. The results showed that the DES (ΔG = −315.06 kJ/mol) formed in a 1:2 mol ratio between urea and ZnCl 2 showed the optimal catalytic activity at 353.15 K, with the product yield as high as 91.50 %, which was significantly better than the traditional non-catalytic system (35.59 %). IR and 1 H NMR spectroscopy confirmed the characteristic peaks of the secondary amine and the carboxylic acid group in urea diacetic acid, and the structural integrity of the product was further verified by the Hinsberg reaction. Mechanistic studies show that DES reduces the reaction activation energy through a dynamic hydrogen bonding network, while the electronic effect of metal salts regulates intermediate release. The urea-ZnCl 2 DES system has high catalytic efficiency and environmental friendliness under mild conditions (80℃), and can be recycled, which provides a new idea for the green industrial production of polyurea materials. This study provides the theoretical basis and practical reference for the multifunctional catalytic application and green chemical process design of DES in organic synthesis.