Side reactions in the oxo process

Conclusions

• 1. In the preparation of carbonyls from metallic cobalt deposited on pumice and carbon monoxide, using an olefinic raw material as solvent, carbonylation of the olefins takes place to an extent which depends on the concentration in the raw material of the cobalt carbonyls formed.

• 2. The temperature of the process has a significant effect on the yields of desired and side products.

• a) At 150–155‡ C the optimum extent of conversion with respect to the yield of aldehydes is reached with 0.7% of cobalt carbonyls in the raw material, At higher concentrations an increased yield of condensation products (50–90%) is observed.

• b) At 190‡ C, even with the maximum concentration of cobalt carbonyls in the raw material (2.7%), there is no increase in the yield of side products since hydrogenation of the aldehydes predominates over the condensation reaction.

• 3. In the thermal decomposition of cobalt carbonyls, 60–70% of the carbon monoxide, which is contained in the carbonyls and dissolved in the product, enters into the carbonylation reaction.

• 4. In the thermal decomposition process, partial hydrogenation of C₅–C₇ aldehydes occurs, to an extent depending on the concentration of cobalt carbonyls. With the content off cobalt carbonyls planned for industrial purposes (0.2–0.3%), there is almost no hydrogenation of the aldehydes.