5-HMF Production in Piperylene Sulfone: A Bifunctional Solvent for Reaction and Separation

5-Hydroxylmethylfurfural has garnered wide interest as a potential bio-based commodity chemical due to its multiple reactive groups and relatively easy formation from fructose and other sugars.  For example HMF can be produced from fructose in DMSO in high yields; however the separation is difficult and wasteful. The literature contains numerous examples of HMF production in DMSO or DMSO and water, separated by extraction into methyl isobutyl ketone. When combined with heterogeneous catalysis from ion exchange resins, the yields become particularly attractive. However in each of these cases, despite the good yields, recovery of the product requires expensive liquid-liquid extraction processes, and often the DMSO is not recyclable, thus rendering the reaction impractical.

To address the difficulties associated with separating HMF from DMSO, we use piperylene sulfone, a solvent with very similar solvatochromic properties to DMSO. These similarities make piperylene sulfone a viable replacement as reaction medium. Piperylene sulfone is formed through a reverse cheletropic reaction between sulfur dioxide and 1,3-trans-piperylene. Superiorly to DMSO, piperylene sulfone can be decomposed to sulfur dioxide and piperylene at temperatures of ~110C which allows for facile separation of reaction products. The off-gassed sulfur dioxide and trans-piperylene can be re-reacted elsewhere to reform the piperylene sulfone, enabling recyclability.

We demonstrate a combined reaction separation system composed of fructose in piperylene sulfone with Amberlyst-15 as catalyst. We will present the results of a statistical design of experiments conducted to optimize conversion of HMF as well as the separation of HMF from piperylene sulfone. We shall also present opportunities for future research using this solvent system.