COMPARATIVE-STUDY OF HOMOGENEOUS CATALYTIC ACTIVITY OF GROUP-8-9 METAL-COMPOUNDS IN HYDROFORMYLATION OF 1-HEXENE

Group 8-9 transition-metal compounds, inorganic chlorides, the corresponding carbonyls, and two mixed-metal carbonyl clusters were studied as homogeneous catalyst precursors in 1-hexene hydroformylation under an equimolar carbon monoxide and hydrogen atmosphere (50 bar) at 100-degrees-C. Of the metals studied, the Co and Rh compounds, both as chlorides and as carbonyls, were the most reactive as 1-hexene hydroformylation catalysts. In addition, Ru3(CO)12 showed a modest hydroformylation activity. The regio-selectivity, i.e., the ratio of linear to branched products, of the catalysts studied was high for cobalt carbonyls as well as for phosphine- and phosphite-modified rhodium carbonyls and low for binary rhodium carbonyls. The addition of NEt3 as a co-catalyst into the hydroformylation solution of RhCl3.3H2O, Rh2(CO)4Cl2, Rh4(CO)12, and Co2Rh2(CO)12 initiated hydrogenation of aldehydes to the corresponding alcohols in high yield (68-100%). A weaker hydrogenation effect was observed in the cases of Ru3(CO)12 and [PPN][RuRh5(CO)16]. However, the presence of phosphine or phosphite on the rhodium catalyst or in the hydroformylation solution prevented almost completely the effect of the amine as a co-catalyst.