Factors effecting the hydrogenation of fructose with a water soluble Ru-TPPTS complex. A comparison between homogeneous and heterogeneous catalysis

Inulin, a polysaccharide containing one D-glucose and 10 to 50 D-fructose units, when hydrolysed and hydrogenated in a one pot approach, would be an attractive D-mannitol feedstock. For this purpose, the hydrogenation was studied with fructose as a model compound, using a water soluble, homogeneous catalyst. This catalyst contains ruthenium as the active metal, and trisulfonated triphenylphosphine (TPPTS, P(m-C6H4SO3Na)(3)), as the ligand. The effects of temperature, pressure, catalyst/substrate and ligand/metal ratios on the activity and selectivity were investigated. The reaction was shown to be homogeneously catalysed, despite the formation of some ruthenium particles at higher temperatures (>90 degrees C), and the active complex was studied with H-1 and P-31 NMR, Addition of HCl or salts (NaCl, Nal and CaCl2) increased the selectivity to D-glucitol and the catalytic activity. Upon deuterogenation of fructose with H-2 in D2O, D was built in only at the 2-position. (C) 1999 Elsevier Science B.V. All rights reserved.