Patent No. U.S. 6,946,563
Assignee: E.I. Du Pont De Nemours and Company, Wilmington, Delaware, U.S.A. Title or Subject: Production of 5-Methyldihydrofuran-2-one from Levulinic Acid in Supercritical Media
Levulinic acid 27 is easily obtained from various cellulose feedstocks and has been the subject of previous patent reviews (Org. Process Res. Dev. 2005, 9, 244). 28 is a useful synthetic intermediate and can also be used to prepare polyesters. The process described here exploits advantages of using supercritical fluids (SCFs) as reaction solvents. The use of SCF-mediated reactions and SCF extraction has seen a significant increase in interest the past few years, and in fact commercial processes are widely used. SCFs are used in this process in the hydrogenation of 27 to 28 as shown in Scheme 7. The catalyst used is a commercially supported Ru that is reduced prior to use. The process is extremely efficient for producing 28 with a 99.5% conversion of 27 and a selectivity of 99.7%, and the patent gives examples of both batch reactions and of a continuous flow method