1-heptene hydroformylation over phosphinated silica-anchored rhodium thiolate complexes

The rhodium (I) pentaflurophenylthiolate complexes [Rh(mu -SC6F5)(COD)](2) and [Rh(mu -SC6F5)(CO)(2)](2) were anchored on phosphinated silica, These catalysts were tested in the hydroformylation reaction of 1-heptene in toluene at 343-393 K using a gas feed ratio of CO:H-2 = 1 mole. The conversion of 1-heptene versus the reaction time followed S-shaped curves in which the induction period depended on the catalyst precursor and number of cycles in the reaction. Selectivity towards linear aldehyde was high, although the extent of isomerisation to internal olefins was found to be important. The addition of free PPh3 to the reaction medium markedly increased the yield to linear aldehyde but the rate of the reaction appeared to be retarded. The results are compared with those obtained on using these complexes in homogeneous phase under similar conditions. The effects of temperature, pressure and the phosphine/Rh mole ratio on the reaction rate and selectivity are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.