VARIOUS APPROACHES TO TRANSFERS IMPROVEMENT DURING BIPHASIC CATALYTICHYDROFORMYLATION OF HEAVY ALKENES

The [HRh(CO)(TPPTS)(3)] precursor, where TPPTS is the water-soluble P( m-C6H4SO3Na)(3) ligand, has opened a large area for the Supported-Aque ous-Phase (SAP) catalysed functionalisation of heavy substrates. We in vestigated several ways to increase the efficiency of heavy alkenes hy droformylation by [Rh-2(mu-(SBu)-Bu-t)(2)(CO)(2)(TPPTS)(2)]. Addition of a cosolvent was shown to lead to a significant leaching of rhodium in the organic phase. Promising results were obtained. First the Delma s-Chaudhari method of adding small amounts of PPh3 to [HRh(CO)(TPPTS)( 3)] to maintain the complex at the interface, was examined for[Rh-2(mu -(SBu)-Bu-t)(2)(CO)(2)(TPPTS)(2)]. Here [Rh-2(mu-(SBu)-Bu-t)(2)(CO)(2) (PPh3)(2)] was rapidly formed and is operating classically in the orga nic phase. Moreover, beta-cyclodextrin was used as a phase-transfer ag ent allowing the inclusion of the substrate and its transport to the a queous phase where the reaction is occurring. Finally, the use of sili ca with various hydration ratios in SAP catalysis led us to propose th at the microreactors containing water, complex and extra TPPTS operate on the surface of the support. (C) 1998 Elsevier Science B.V. All rig hts reserved.