Merging theBiobased Platform Chemicals 5‑Hydroxymethyl-2-furfural(5-HMF) and Succinic Anhydride toward a Novel Hydroxy Acid Monomerfor Polyester Production

In this study, we introduce the chemical synthesis and kilogram-scale production of the novel monomer 4-((5-(hydroxymethyl)furan-2-yl)-methoxy)-4-oxobutanoic acid (HFBA), which is based on the biobased platform chemicals 5-hydroxymethyl-2-furfural (5-HMF) and succinic anhydride as starting materials. The synthesis process involves an initial straightforward ring-opening reaction of succinic anhydride with the hydroxy moiety of 5-HMF, yielding the adduct 4-((5-formylfuran-2-yl)-methoxy)-4-oxobutanoic acid (FFBA) in quantitative yield. The aldehyde functionality of FFBA is then selectively reduced under formation of the desired novel hydroxy acid monomer HFBA. The scalability of this efficient two-step process was successfully demonstrated already on a 1 kg scale, with an overall yield exceeding 99%. Furthermore, this new monomer possessing bifunctional hydroxy acid properties can be readily polymerized to form the fully biobased polyester poly(2,5-furandimethylenesuccinate) (PFMS). The resulting biobased polyester exhibits a glass transition temperature of 50 °C and a melting temperature of 180 °C. At 230 °C, polymer decomposition occurs, leading to the release of pure succinic acid. This decomposition can also contribute to a future strategy for recovery of the succinic acid monomer and thus to a chemical recycling strategy. It is further noteworthy that the polymer demonstrates strong adhesive properties when being applied as glue to surfaces from different material origin such as plastics, wood, or metal, surpassing even commercially available nonbiobased adhesives. HFBA has been readily polymerized to form the biobased polyester poly(2,5-furandimethylenesuccinate) (PFMS), which was characterized comprehensively and demonstrated strong adhesive properties.