Studies on the experimental variables effects on rhodium catalyzed hydroformylation of unsaturated fatty esters and comparison of [RhH(CO)(PPh 3)3] and [RhCl3.3H2O] as starting catalytic precursors

Abstract

Hydroformylation experiments were performed with technical-grade methyl oleate (MO) and soybean oil (SO) using [RhH(CO)(PPh3)3] and [RhCl3.3H2O] (double bond/Rh = 745) as catalyst precursors modified or not by triphenylphosphine. [RhH(CO)(PPh3) 3] shows 100% conversion and 80-91% selectivity to aldehydes in only 4h for both substrates under mild conditions (100°C, 40 bar, CO/H 2 = 2:1, ligand/Rh = 10:1). Despite the rapid isomerisation of the soybean oil, producing trans isomers and conjugated dienes, no effects were observed on its further conversion to aldehydes. The reaction of soybean oil conducted with pure [RhCl3.3H2O] produced only conjugated dienes, and when this precursor was modified with triphenylphosphine (ligand/Rh = 10:1) no reaction was observed at all. Curiously, yellow crystals corresponding to the complex [Rh(Cl)(CO)(PPh3)2] were quantitatively isolated at the end of the reaction. ©2005 Sociedade Brasileira de Química.