Solely Biomass‐Derived Polyethylene Terephthalate (PET): Conversion of Bio‐based Isoprene and Acrolein to p ‐Xylene and Terephthalic Acid

Abstract There exist significant challenges in the synthesis of solely biomass‐derived p ‐xylene and terephthalic acid (TPA), the monomer precursors of polyethylene terephthalate (PET). Herein, we describe a flexible synthetic route to prepare either p ‐xylene or TPA from biomass‐derived isoprene and acrolein, which avoids harsh reaction conditions such as high pressure or extreme low temperature. The route starts from 4‐methyl‐cyclohex‐3‐enecarbaldehyde, the product of Diels‐Alder reaction of isoprene and acrolein. Then p ‐xylene was successfully obtained by subsequent reduction and aromatization reactions using either environment‐friendly solvents or in neat. In addition, this route was further modified for a process to prepare both p ‐xylene and TPA. By using the same intermediate after Diels‐Alder reaction, an aromatization reaction was followed by a reduction to p ‐xylene or an oxidation to directly TPA in an overall yield of 32% over three steps.