Simultaneous Synthesis of Poly(ethylene glycol succinate) Oligomers and Dimethyl Carbonate Using Metal Acetates as Catalysts

Simultaneous synthesis of poly(ethylene glycol succinate) oligomers and dimethyl carbonate(DMC) was achieved by coupling reaction of ethylene carbonate(EC) and dimethyl succinate(DS) over various metal acetate catalysts.The effluent of coupling reaction was confirmed by GC-MS qualitative analysis.The structure of poly(ethylene glycol succinate) oligomeric product was characterized and assured by 1H NMR and FTIR spectra,and the intrinsic viscosity of poly(ethylene glycol succinate) oligomers was tested by the Ubbelohde type viscometer.The yield of DMC was gained by gas chromatography quantitative analysis,and the extent of coupling reaction could be calculated by the yield of DMC.Results showed that the lithium acetate has the highest catalytic activity.Using this compound as catalyst,the effects of experimental parameters including the molar ratio of EC to DS,reaction temperature,reaction time and amount of catalyst on the coupling reaction were investigated.The optimized reaction conditions are as follows:reaction temperature is in the range of 195 to 200 ℃,molar ratio of EC to DS is 2:1,the molar fraction of catalyst is about 2%,reaction time is 2 h.Under these conditions,the yield of DMC was 48.0% ;the intrinsic viscosity [η]of poly(ethylene glycol succinate) oligomers was 0.3787 dL/g.