Production of Diethyl Terephthalate from Biomass‐Derived Muconic Acid

We report a cascade synthetic route to directly obtain diethyl terephthalate, a replacement for terephthalic acid, from biomass‐derived muconic acid, ethanol, and ethylene. The process involves two steps: First, a substituted cyclohexene system is built through esterification and Diels–Alder reaction; then, a dehydrogenation reaction provides diethyl terephthalate. The key esterification reaction leads to improved solubility and modulates the electronic properties of muconic acid, thus promoting the Diels–Alder reaction with ethylene. With silicotungstic acid as the catalyst, nearly 100 % conversion of muconic acid was achieved, and the cycloadducts were formed with more than 99.0 % selectivity. The palladium‐catalyzed dehydrogenation reaction preferentially occurs under neutral or mildly basic conditions. The total yield of diethyl terephthalate reached 80.6 % based on the amount of muconic acid used in the two‐step synthetic process.