Synthesis of levulinic acid and derivatives from muconic acid

One of the major challenges of our time is the transformation of our petroleum based industry towards a more sustainable model based on other carbon sources. Indeed, the global warming combined with an ever growing world population make this matter more actual than ever. This has driven chemists to look into alternative feedstocks for the chemical industry, with non-edible biomass (e.g. lignocellulose from plant waste) being a particularly attractive candidate. In the so-called “biorefinery”, this is transformed into "platform chemicals”, which can subsequently be transformed into a broad range of other molecules with a wide variety of applications. Levulinic acid is named one of the key biorenewable platform molecules, with its derivatives spanning from solvents and biofuel additives, to pharmaceuticals and plasticizers. It is currently produced industrially from non-edible sugars such as xylan or cellulose. However, these methods are lacking as they require corrosive acid catalysts, suffer from rather low yields and experience char formation in the form of humins. It comes as no surprise that levulinic acid is currently only produced in small scales and that there is an ongoing search for new production methods from biorenewable feedstocks. ​ ​ In this PhD thesis, an alternative route to levulinic acid is explored, starting from another biorenewable platform chemical called muconic acid. This can be produced from lignocellulose through both chemical and biotechnological means. It was discovered that simply heating muconic acid in high-temperature pressurized water can efficiently form levulinic acid in high yields, without requiring additional reagents or complicated separations. This method was demonstrated to work on real bio-based feedstocks, such as pine wood and muconic acid produced by yeast fermentation of sugars. Furthermore, the method was successfully adapted for the direct synthesis of value-added levulinate esters.