Dialkyl Carbonate Synthesis Using Atmospheric Pressure of CO₂

Dialkyl carbonates (DRCs) are valuable compounds widely used in the industry. The synthesis of DRC from CO₂ has attracted interest as an alternative to the current method, which uses phosgene. However, the reported approaches for DRC synthesis from CO₂ requires high-pressure and high-concentration CO₂, resulting in elevated costs associated with CO₂ purification and manufacturing facilities. In this report, we present an environmentally friendly method for producing DRC from low-concentration and low-pressure CO₂ via a dehydration condensation approach without the use of halogenated alkylating agents. This method involves the formation of monoalkyl carbonate [BASE-H][ROC(O)O] using a strong organic base and alcohols, tetraalkyl orthosilicates as dehydrating agents, and CeO₂ as the catalyst. Using the method, 39 and 30% of diethyl carbonate yields were accomplished with only 100 and 15 vol % CO₂ (CO₂/N₂ = 15:85) gas bubbling at atmospheric pressure, even under reaction conditions with no large excess of either CO₂, alcohol, or dehydration agent.