CATALYTIC ACTIVITY OF RUTHENIUM 2,2'-BIPYRIDINE DERIVED CATALYSTS IN 1-HEXENE HYDROFORMYLATION AND 1-HEPTANAL HYDROGENATION

Method and conditions of preparation strongly affect the hydroformylation activity of the ruthenium cluster derived Ru-3(CO)(12)/2,2'-bipyridine/SiO2 catalyst. The highest activities have been achieved with a dichloromethane impregnated catalyst. A major problem with this catalyst is poor reproducibility of the hydroformylation activity, probably due to uncontrolled formation of several supported surface species, Reproducibility can be improved by using a non-chlorinated impregnation solvent such as tetrahydrofurane. In hydroformylation, Ru-3(CO)(12)/2,2'-bipyridine/SiO2 has a strong tendency to convert alkenes directly to alcohols. The limiting step in this process is the initial hydrocarbonylation of alkenes to aldehydes. Ru-3(CO)(12)/2,2'-bipyridine/SiO2 catalyzes the second step, hydrogenation of aldehydes to alcohols, in good yield. Use of an effective, aldehyde-producing cocatalyst such as Rh together with Ru-3(CO)(12)/2,2'-bipyridine/SiO2 allows very high alcohol yields to be achieved. The detailed surface structure of Ru-3(CO)(12)/2,2'-bipyridine/SiO2 is not known, but one probable active species is oligomeric or polymeric [{Ru(bpy) (CO)(2)}(n)]. Monomeric and dimeric ruthenium monobipyridines showed at most only moderate activity in hydroformylation. By contrast, [Ru(bpy)(CO)(2)Cl(C(O)OCH3)] and [Ru(bpy)(CO)(2)ClH] are highly active in hydrogenation of C-7 aldehydes to C-7 alcohols.