Assessment of organic solvents for 2,5-furandicarboxylic acid (FDCA) and distribution in water/cyclohexanone biphasic system

2,5-furandicarboxylic acid (FDCA) is one of the most promising sugar-derived building blocks aimed to produce greener polymers, such as the 100 % recyclable bioplastic polyethylene furanoate (PEF). One incipient field of research is the development of liquid?liquid biphasic systems for FDCA production from 5-hydroxymethylfurfural (HMF) to increase selectivity and minimize undesirable by-product formation. In this work, we first performed an assessment of potential organic green solvents to form biphasic systems considering operability, along with safety, health, and environmental implications. This analysis guided the selection of eight organic solvents in which the solubility of FDCA was measured: cyclohexanone, diethyl ether, isobutyl acetate, methyl isobutyl ketone, methyl ethyl ketone, methoxycyclopentane, tert-butylmethyl ether, and octan-1-ol. The results revealed the superior performance of cyclohexanone as a solvent for the organic phase/water FDCA distribution owing to its higher FDCA solubility (1.364 g/L at 293.15 K). Thus, the FDCA distribution coefficient (KFDCA) between water and cyclohexanone was examined at several temperatures (293.15-313.15 K) and various initial aqueous concentrations to gain deeper insight into the thermodynamics of the phase transfer process and the influence of pH on FDCA distribution between water and cyclohexanone. The resulting enthalpy and entropy of transfer were -15.3 ± 1.0 kJ moll-¹ and -44.9 ± 4.6 J K-¹ mol-¹, thus the highest value of KFDCA (4.83) was obtained at 293.15 K, together with a very high separation factor (81.5) which shows the great potential of cyclohexanone to extract FDCA from aqueous solutions

This research has been performed in the framework of project P232 of the Universidad de Cantabria. F.P. acknowledges grant IJC2020- 043134-I funded by MICIU/AEI/10.13039/ 501100011033 and EU NextGenerationEU/PRTR. J.E. gratefully acknowledges The University of Manchester for funding.