Biphasic hydroformylation of olefins using a novel water soluble rhodium polyethylene glycolate catalyst

The highly reactive water-soluble hydroformylation catalyst, rhodium polyet hylene glycolate (Rh(PEG),), prepared by the reaction of polyethylene glyco l and rhodium trichloride hydrate, was used as a catalyst for hydroformylat ion reactions of olefins, such as dodec-1-ene, 2.4.4-trimethylpent-1-ene an d styrene, in biphasic systems. The reactions were done in a broad temperat ure range and at a pressure range from 7 to 12 MPa. Turnover frequency for the catalytic reaction of the low reactive 2.4.4-trimethylpent-1-ene is 450 (mol aldehyde/mol Rh x h), which is 3 times higher than in comparable homo geneous rhodium systems. The selectivity for aldehydes is excellent(> 98%). The dependence of the conversion vs. time was monitored for different part ial pressures, pH values, temperatures and catalyst concentrations. Activat ion parameters have been calculated for the hydroformylation of the olefins in water and polyethylene glycol with rhodium polyethylene glycolate as a precatalyst. The activation energy in water is calculated for the hydroform ylation of various olefins (dodec-1-ene E-a 95 kJ/mol, 2.3.3-trimethylpent- 1-ene E-a 30 kJ/mol and styrene E-a 33.1 kJ/mol). The hydroformylation reac tion with rhodium polyethylene glycolate as a precatalyst is first-order fo r dodec-1-ene and 2,4,4-trimethylpent-1-ene and zero-order for styrene. (C) 2000 Elsevier Science B.V. All rights reserved.