Synthesis of glycerol carbonate from glycerol and propylene carbonate using deep eutectic solvent NaHCO3: glycerol as a catalyst

A series of deep eutectic solvents (DESs) with NaHCO 3 as hydrogen bond acceptor and glycerol (GL) or ethylene glycol (EG) as hydrogen bond donor are prepared and used as catalyst for the synthesis of glycerol carbonate (GC) from the transesterification of GL and propylene carbonate (PC). FT-IR, NMR, TGA and DSC are used for the characterization of the physicochemical properties of prepared DESs. The effects of reaction temperature, PC to GL molar ratio, catalyst amount, and reaction time on the GL conversion and GC yield are investigated in detail. The results show that NaHCO 3 :GL (1:5) DES possesses the highest catalytic activity, which is attributed to the hydrogen bond network structure between NaHCO 3 and GL as well as the interaction between NaHCO 3 :GL DES and reactants GL or PC. Under 135 °C, PC/GL molar ratio of 2:1, catalyst amount of 5 wt% (based on the GL weight), and reaction time of 4 h, the GL conversion of 99.99% and GC yield of 99.54% are obtained. NaHCO 3 :GL (1,5) DES can be reused five times with no obvious decline in activity. Based on the experimental results and FT-IR analysis, the reaction mechanism of transesterification of GL and PC using NaHCO 3 :GL (1,5) as catalyst is proposed. To the best of our knowledge, this is the first report about the application of DES catalyst for the reaction of GL and PC.