On the Diels–Alder Approach to Solely Biomass‐Derived Polyethylene Terephthalate (PET): Conversion of 2,5‐Dimethylfuran and Acrolein into <i>p</i>‐Xylene

Abstract Polyethylene terephthalate (PET) is a polymeric material with high global demand. Conventionally, PET is produced from fossil‐fuel‐based materials. Herein, we explored the feasibility of a sustainable method for PET production by using solely bio‐renewable resources. Specifically, 2,5‐dimethylfuran (derived from lignocellulosic biomass through 5‐(hydroxymethyl)furfural) and acrolein (produced from glycerol, a side product of biodiesel production) were converted into the key intermediate p ‐xylene (a precursor of terephthalic acid). This synthesis consists of a sequential Diels–Alder reaction, oxidation, dehydration, and decarboxylation. In particular, the pivotal first step, the Diels–Alder reaction, was studied in detail to provide useful kinetic and thermodynamic data. Although it was found that this reaction requires low temperature to proceed efficiently, which presents a limitation on economic feasibility on an industrial scale, the concept was realized and bio‐derived p ‐xylene was obtained in 34 % overall yield over four steps.