Poly(ethylene glycol) based bis-diol as a functional medium for highly efficient conversion of urea and methanol to dimethyl carbonate

Dimethyl carbonate (DMC) is a useful chemical and can substitute some toxic substances. The synthesis of DMC from methanol and urea is an attractive route, but is a thermodynamically unfavourable reaction. Enhancing the equilibrium conversion of the reaction is an intereting topic. In this study, we demonstrate that poly(ethylene glycol) diglyceryl ether (PEGDE, a poly(ethylylene glycol) based bis-diol), which is a non-toxic and cheap polymer, can be used as a functional medium for the synthesis of DMC from methanol and urea using ZnO as the catalyst. In the PEGDE/ZnO catalytic system, PEGDE reacted with urea to form poly(ethylene glycol) di(2,3-carbonate glyceryl) ether (PEGDC), and the reaction equilibrium was shifted by sweeping away the generated ammonia. Then, DMC was produced after methanol was added and PEGDE was regenerated and the PEGDE/ZnO catalytic system could be reused directly. It was shown that a very high equilibrium yield could be achieved.