EXPANDED SCOPE OF SUPPORTED AQUEOUS-PHASE CATALYSIS - EFFICIENT RHODIUM-CATALYZED HYDROFORMYLATION OF ALPHA,BETA-UNSATURATED ESTERS

The use of supported aqueous-phase (SAP) catalysts for the rhodium-bas ed hydroformylation of methyl acrylate leads under optimal conditions to much higher activities than those observed under comparable homogen eous and biphasic conditions. The results obtained with a series of ac rylic esters are found to be dependent on the water content of the sol id support and on the solubility of the functionalized olefin in water . For soluble organic reactants, like methyl acrylate, optimal activit ies are obtained for fully filled pore volume materials. For less solu ble organic reactants, like butyl acrylate, hydroformylations are best achieved with a lower degree of pore filling, strictly dependent on t he nature of the functionalized olefin. It is assumed that the reactio n of hydrophilic olefins occurs mainly in the homogeneous water film d ispersed over the solid support, whilst that of lipophilic olefins tak es place at the interface between the organic phase and the aqueous fi lm. The effects of temperature and the nature of the solid support are reported. Experiments are described that indicate that the surface ar ea and the chemical nature of the solid play a major role on the activ ity of the SAP catalyst, whilst the pore diameter has almost no influe nce. However, a decrease in the activity of methyl acrylate hydroformy lation was observed upon recycling of the SAPC materials, which was at tributed to the leaching of rhodium into the organic phase and the gra dual dehydration of silica. (C) 1996 Academic Press, Inc.