Homogeneous Hydrogenation of Aldehydes under Hydroformylation Conditions

Homogeneous Hydrogenation of Aldehydes under Hydroformylation Conditions 

In the previous sections, it has been pointed out several times that the aldehyde group formed in the hydroformylation reaction can be subsequently hydrogenated to the hydroxyl group in the oxo reactor. It has been found that in most cases, if the stability of the cobalt hydrocarbonyl 

The hydrogenation reaction requires a certain minimum temperature. This is generally above about 140-150 °C below this temperature, only aldehyde is usually isolated after the hydroformylation. 

The hydrogenation is first order in aldehyde, cobalt and hydrogen concentration. The carbon monoxide pressure has a similar effect to that observed in the hydroformylation reaction [325] (see fig. 10). 

The reaction rate increases with increasing carbon monoxide pressure (until all the cobalt remains as carbonyl) and then falls off markedly. The decrease in rate of hydrogenation is substantially greater than that found for hydroformylation and is proportional to the second power of the CO partial pressure [325]. 

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