Nowadays solvent use in industry is facing increasing regulatory and commercial pressure due to tightening legislation and an evolving awareness of health and safety issues. In parallel, growing environmental concerns over the source and life cycle of common solvents encourage the development of bio-based alternatives that can compete with petroleum-derived counterparts.

Lignocellulosic biomass is a promising feedstock for the production of renewable solvents since it is available in large quantities and does not compete with food crops. Several biomass-derived solvents have been developed and commercialized so far. However, their use in industry is still considered problematic due to various reasons such as high production cost (GVL, Dimethyl isosorbide), high flammability (2-Me-THF), instability in harsh conditions (Cyrene, cyclic carbonates). Newly emerging candidates that aim to replace hazardous analogs are also facing challenges. In this regard, acetal-stabilized xylose derivatives that can be inexpensively produced directly from biomass at over 90% yield (on a xylan basis) by aldehyde-assisted fractionation technology developed in our lab could be interesting candidates for use as solvents¹.

In this work, we explored diformylxylose (DFX) and its derivatives as potential solvents by assessing their performance in model reactions, as well as measuring their physical and solvatochromic parameters. DFX was found to have similar solvation properties to conventional polar aprotic solvents such as NMP, DMF, DMAc, while DFX’s derivatives were closer to medium-polarity solvents such as acetone and THF, according to a comparison of Kamlet-Abboud-Taft parameters. The specific properties of DFX made it a promising component of deep eutectic solvents, which were also prepared in this work. Hansen Solubility Parameters indicated that DFX has high similarity to Dimethyl Isosorbide while being potentially much less expensive. At the same time, DFX's derivatives can complement the list of conventional ethers and ketones, while bringing new physical properties and, possibly, a safer profile. 

Notably, we demonstrated that performance of the developed solvents in alkylation, cross-coupling, and hydrogenation reactions was comparable with conventional problematic analogs and in some cases outperforming existing green alternatives². DFX was also found to have potential in many other applications including polymer synthesis, solid-phase peptide synthesis, biomass processing, liquid exfoliations, etc.

A preliminary toxicological assessment (bacterial Ames test) performed on DFX showed that this molecule is unable to cause mutations both directly and indirectly and cannot be considered a mutagenic compound. 

Finally, we demonstrated that DFX and its derivatives can be produced sustainably from biomass, specifically corn cobs in a kg-scale. This shows an excellent example of how waste biomass can be valorized into valuable chemicals with relatively low cost and high efficacy. A life cycle assessment has been performed, which demonstrated high competitiveness of this new class of solvents against conventional analogs.