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.