Catalytic hydrogenation of levulinic acid in aqueous phase

The hydrogenation of levulinic acid (LA) yielding gamma-valerolactone (GVL) has been examined in aqueous solution using various water soluble phosphine ligands in combination with the metal precursors [Ru(acac)(3)] and [RuCl3]. Using catalyst loadings of only 0.2 mol%, GVL could be obtained in yields up to 99% conversion and 97% selectivity along with a maximum turnover frequency of 200 mol(GVL) mol(Ru)(-1) h(-1) within 5 h, using 3,3',3 ''-phosphinidynetris(benzenesulfonic acid) trisodium salt (TPPTS) and Ru(acac)(3) as catalytic system. In addition, a ruthenium-phosphine complex immobilized on the amphiphilic copolymer PS-PEG was examined under the same conditions and gave 90% conversion of LA in 24 h. (C) 2012 Published by Elsevier B.V.