Catalytic Olefin Hydroformylation An important industrial reaction is the catalytic hydroformylation reaction, also known as oxo-process (Figure \(\PageIndex{1}\)). It was discovered in 1938 by Otto Roelen at BASF. In the hydroformylation reaction an H atom and a formyl group are added to an alkene to form aldehydes. The reaction can produce both branched an linear aldehydes from terminal alkenes, CO, and H 2 using a carbonyl hydrides such as HCo(CO) 4 as a catalyst. The reaction is performed at about 100°C at a pressure of up to 100 atm. Mechanism of the Catalytic Olefin Hydroformylation by HCo(CO) 4 How does the hydroformylation work mechanistically? The mechanism is illustrated for the hydroformylation of propene (Fig. \(\PageIndex{2}\):). The actual catalyst HCo(CO) 4 is first formed from its precatalyst Co 2 (CO) 8 in the presence of H 2 in a dinuclear oxidative addition reaction. The catalyst can undergo a substitution reaction in which a CO ligand is replaced by the olefin that binds side-on to the cobalt. This species can then undergo a migratory olefin insertion reaction. This leads to a mixture of linear and branched alkyl groups attached to the Co. A new CO ligand can add to the vacant site. The alkyl group can then insert into a carbonyl group in another migratory insert step, and the vacant site can be reoccupied by a new CO molecule. Then, H 2 is added in an oxidative addition. This is the slowest and rate-limiting step in the catalytic cycle. From the addition product the aldehyde can then be eliminated in a reductive elimination reaction. Addition of CO regenerates the catalyst, and the catalytic cycle can begin again. Hydrocarbonylations After the hydroformylation, a number of other hydrocarbonylations were developed, and industrially deployed. When hydrogen is replaced by H 2 O hydrocarboxylations of alkenes lead to carboxylic acids (Fig. \(\PageIndex{3}\):). With an alcohol instead of H 2 hydroalkoxycarbonylcations lead to esters. The employment of amines instead of H 2 leads to amides in hydroamidocarbonylation reactions.