Alkenes in hydroformylation

The cobalt-catalyzed reaction of carbon monoxide and hydrogen with an alkene, hydroformylation, is an extremely important industrial process, but it occurs under vigorous conditions (200-400 bar, 150-200 °C) and is not a particularly selective reaction. In the presence of ligand-modified rhodium catalysts, however, hydroformylation can be carried out under extremely mild conditions (1 bar, 25 C). The catalytic activity of such rhodium complexes is in fact lO -Ky times greater than that of cobalt complexes and side reactions, such as hydrogenation, are significantly reduced. The reactivity of alkenes in hydroformylation follows a similar pattern to that observed in other carbonylation reactions, i.e. linear terminal alkenes react more readily than linear internal alkenes, which in turn are more reactive than branched... 

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