CO2‐Enhanced Production and Synthesis of 2,5‐ Furandicarboxylic Acid under CO2 Flow through Henkel Reaction

The present study investigated the preparation of 2,5‐furandicarboxylic acid (FDCA) via the Henkel reaction between furoic acid alkali metal salts and zinc chloride under a continuous CO2 flow at atmospheric pressure. The results obtained were compared with those of previous studies that used high‐pressure conditions or toxic cadmium catalysts. The pathways and rate‐determining steps of the reaction are revealed for the first time. Furthermore, the enhanced formation of FDCA through the promotion of carboxyl exchange and rearrangement during the reaction under a CO2 flow was examined. The CO2‐rich environment afforded a high FDCA yield of 86.30 %, which is the highest yield obtained to date using the Henkel reaction. The findings of this study offer economically improved conditions for large‐scale FDCA production. The pathways and rate‐determining steps of the preparation of 2,5‐furandicarboxylic acid are identified. The approach includes CO2 flow via the Henkel reaction. The improvements include the mild operating conditions such as atmospheric condition and highest yield among the literatures.