2,5-Furandicarboxylic Acid Synthesis and Use
The structural similarity of 2,5‐furandicarboxylic acid (FDCA) to purified terephthalic acid (PTA), a petroleum commodity intermediate for the preparation of polyethylene terephthalate (PET), has made FDCA a popular biobased alternative in the fabrication of plant‐based soft drink bottles. Studies suggest that FDCA‐derived polyester has barrier properties several times higher than that of PET, while its mechanical properties are comparable to those of their petroleum counterparts. FDCA is a versatile biobased building block synthesized by the catalytic oxidation of 5‐hydroxymethylfurfural (HMF) and its derivatives or directly from carbohydrates. In the past decade, industrial efforts have focused on integrating FDCA synthesis into existing PTA production lines by applying the commonly known Amoco Mid‐Century (MC) catalyst for aerobic oxidation of HMF in acetic acid. The current focus is now directed instead to the search for efficient catalysts and processing conditions to prepare FDCA in an environmentally benign solvent such as water. Studies indicate that supported precious metal catalysts provide high selectivity for the oxidation of HMF into FDCA under controlled conditions. Oxidation of HMF in a basic condition proceeds through the oxidation of the aldehyde moiety of HMF followed by oxidation of the alcohol group of the resulting intermediate to produce FDCA. The challenges of aqueous phase oxidation are the stability of HMF and degradation of metal catalysts. Considering its unique structure and biomass origin, researchers and industries are envisioning enormous market potential for FDCA in the production of polyesters, polyamides, polyurethanes, thermosets, and plasticizers.