Sustainable Production of Pyromellitic Acid from Biomass-Derived Furanic Platform Chemicals

Aromatic poly(carboxylic acid)s, especially terephthalic
acid and pyromellitic acid, are extremely important monomers for polyester
and polyimide manufacture. Current industrial processes predominantly
rely on halogen-promoted oxidation reactions, which require specialized
equipment and cause serious environmental pollution. Herein, a novel
route was developed to synthesize pyromellitic acid from biomass-derived
furanic platform chemicals. The process begins with a Diels–Alder
reaction between furan and dimethyl acetylenedicarboxylate, forming
an oxygen-bridged cyclohexadiene structure with a yield of 84.4%,
and the cycloaddition strategy can also be applied to a variety of
substituted furan-based feedstocks. The central diene of dimethyl
furan-3,4-dicarboxylate was achieved via a cascade of selective hydrogenation
and a retro-Diels–Alder reaction, with an isolated two-step
yield of 92.8%. Subsequently, Diels–Alder, deoxy-aromatization,
and hydrolysis reactions were integrated to efficiently produce pyromellitic
acid, achieving yields higher than 91.3% in each step. Hence, the
overall yield of the target product was approximately 65.1%, originating
from furan. Preliminary green metrics and life cycle assessment were
conducted to calculate the consumption and emissions of the process,
thereby indicating its potential environmental friendliness. This
work provides an effective methodology for the synthesis of crucial
aromatic compounds through the precise design of Diels–Alder
and retro-Diels–Alder reactions, paving the way for the production
of environmentally friendly polyimide materials from renewable biomass.