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ISU researchers have demonstrated an inexpensive, commercially available material, as an effective catalyst for the disproportionation or isomerization of armatic carboxylates to dicarboxylates, allowing for new production routes to valuable polymers such as PET and PEF.

Dicarboxylic acids, such as terephthalic acid or 2,5- furandicarboxylic acid, are commonly used in polyesters such as polyethylene terephthalate (PET), the most common polyester (over 30 million tons produced per year). Polyethylene Furoate (PEF) is an emerging possible replacement to PET in part because of the reduced oxygen permeability of PEF and because of PEF's bio-renewable feedstock. For PET, current production of the dicarboxylic acid monomer relies on the oxidation of petrochemically derived hydrocarbons (such as p-xylene). For current PEF production, the monomer, furandicarboxylic acid, requires 5-hydroxymethyl furfural (HMF). The short shelf life of HMF generates synthetic challenges for this conversion, however. The Henkel process allows for the generation of 2,5- furandicarboxylic acid from the stable precursor potassium furoate, but the state-of-the-art conditions for this reaction requires toxic cadmium catalysis and high temperatures that make it industrially difficult to implement. Iowa State University researchers have developed a method to produce PET and PEF with the use of green, non-toxic salts via the Henkel reaction.

• Low cost

• Non-toxic

• Low temperature reaction

• Bio-renewable feedstock