2‐formyl‐5‐(hydroxymethyl)furan (HMF) derivatives as active complexing agent for CO2 insertion reaction

Renewable-based furan compounds derived from 2-formyl-5-(hydroxymethyl)furan (5-HMF) were successfully employed as catalysts to synthesize cyclic organic carbonates through the reaction of carbon dioxide with epoxides. The effects of temperature, reaction time, reagent ratios, and carbon dioxide pressure were optimized before evaluating various bio-based complexing agents in combination with different alkali metal halide salts. Among them, 2,5-bis(hydroxymethyl)tetrahydrofuran (BHTHF) showed the highest efficiency as a complexing agent when paired with sodium bromide (NaBr), enabling the production of industrially relevant cyclic carbonates in high yields (12 examples, achieving 94-99% epoxide conversion and 70-99% carbonate selectivity) under mild pressure conditions (carbon dioxide pressure of 1-10 bar, reaction time of 6 hours, and temperature of 120 °C). Additionally, the BHTHF/NaBr catalytic system demonstrated high stability, maintaining its performance over nine consecutive epoxide additions (8 mmol each) without any loss of efficiency.