Dialkyl Carbonate Synthesis Using Atmospheric Pressure of CO₂

Abstract

Dialkyl carbonates (DRCs) are valuable compounds widely used in the industry. The synthesis of DRC from CO 2 has attracted interest as an alternative to the current method, which uses phosgene. However, the reported approaches for DRC synthesis from CO 2 requires high-pressure and high-concentration CO 2 , resulting in elevated costs associated with CO 2 purification and manufacturing facilities. In this report, we present an environmentally friendly method for producing DRC from lowconcentration and low-pressure CO 2 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 CeO 2 as the catalyst. Using the method, 39 and 30% of diethyl carbonate yields were accomplished with only 100 and 15 vol % CO 2 (CO 2 /N 2 = 15:85) gas bubbling at atmospheric pressure, even under reaction conditions with no large excess of either CO 2 , alcohol, or dehydration agent.