Propylene oxide as a dehydrating agent: potassium carbonate-catalyzed carboxylative cyclization of propylene glycol with CO2 in a polyethylene glycol/CO2 biphasic system

Abstract

The synthesis of propylene carbonate (PC) from 1,2-propylene glycol (PG) and CO₂ was smoothly performed in a PEG₈₀₀ (polyethylene glycol)/CO₂ biphasic system with K₂CO₃ as a catalyst and propylene oxide (PO) as a dehydrating agent. In the reaction of PG with CO₂, PO presumably removes the water produced, and simultaneously generates more PG, both of which shift the thermodynamic control process and thus accelerate the PC synthesis. The PC yield directly from PG and CO₂ reached 78% under relatively mild reaction conditions (4 MPa, 120 °C, 10 h). Notably, no additional by-product was detected in this process, resulting in economic benefits and the ease of workup procedure.