(708b) Elucidating the Pathway: Catalyst-Driven Muconic to Levulinic Acid Conversion at Mild Conditions

We demonstrate a facile and efficient decarboxylation of neat cis-cis-muconic acid (MA) to levulinic acid (LA) under mild conditions. LA, a US Dept of Energy Top 12 biomass-derived platform molecule, is a key precursor to biofuels, fuel additives, in addition to a host of other specialty chemicals and materials applications. Although several routes for LA synthesis are known, the exact mechanism has remained inconclusive. To fill this gap, we conducted a series of sulfuric acid catalysed experiments with varied amounts of water, ethanol, and chloroform. A suite of NMR techniques—including 1H-NMR, 13C-NMR, and 2-D correlation methods such as heteronuclear single quantum coherence spectroscopy (HSQC)and homonuclear correlation spectroscopy (HCOSY)—were employed in conjunction with gas chromatography-mass spectrometry (GCMS) analysis and DFT calculations to elucidate the intermediates involved in LA synthesis. Kinetic studies revealed rate constants for the consumption of MA and the formation of LA, with activation energies calculated to be 16.1 kJ/mol and 158.18 kJ/mol, respectively. The results indicated 100% selectvity for LA under solvent free conditions. This comprehensive approach not only clarifies the mechanism of LA synthesis from MA but also sets the stage for optimizing this route for industrial applications.