A two-step efficient preparation of a renewable dicarboxylic acid monomer 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] from D-fructose and its application in polyester synthesis
D-Fructose was converted to the dialdehyde 5,5′-[oxybis(methylene)]bis[2-furaldehyde] by heating at 110 °C in DMSO with the Dowex 50 W X8 solid acid catalyst in 76% yield without the isolation of the intermediate 5-hydroxymethylfurfural. This dialdehyde was then converted to the dicarboxylic acid monomer, 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid], using oxygen (1 atm.) and 5% Pt/C catalyst in 1.5 M aqueous NaOH at room temperature in 98% yield. The new dicarboxylic acid monomer can be considered as a renewable resource based alternative to terephthalic acid as demonstrated by the preparation of polyesters with 1,2-ethanediol and 1,4-butanediol in 87–92% yield.