One-Step Conversion of Biomass-Derived Furanics into Aromatics by Bronsted Acid Ionic Liquids at Room Temperature

Aromatics play essential and unique roles in the areas ranging from synthetic chemistry to the manufacturing industry. Production of aromatics from biomass is of great fundamental interest and practical importance to ease the burden of fossil resources. This work delineates a one-step route for the synthesis of renewable aromatics from various biobased furanics and dienophiles by acidic ionic liquids at mild conditions. [Bmim]HSO4 was used as a catalyst and solvent for the direct conversion of 2,5-dimethylfuran and acrylic acid into p-xylene and 2,5-dimethylbenzoic acid; up to 89% aromatic selectivity was achieved at 87% conversion of 2,5-dimethylfuran at room temperature and atmospheric pressure, and totally 84% selectivity of p-xylene can be obtained with a subsequent decarboxylation reaction. The reaction mechanism study supplemented with isotopic tracing and DFT calculations revealed the lowest-energy pathway for the two main products. Various starting materials were studied for further extensions of the method, and it turned out that electron-donating methyl groups on the furan ring played crucial roles on the activation of dehydration and decarboxylation processes. This work provided convenient access to industrial commodity aromatics from fully biomass-derived feedstocks and thus can be regarded more economically and environmentally feasible.