The hydroformylation (oxo) reactions offer ways of converting a-olefins to aldehydes and/or alcohols containing an additional carbon atom.
CH3CH=CH2 + CO + H2 ? CH 3CH2CH2CHO
CH3CH2CH2CHO + H2 ? CH3CH2CH2CH2OH
In the process (Fig. 1), the olefin in a liquid state is reacted at 27 to 30 MPa and 150 to 170oC in the presence of a soluble cobalt catalyst. The aldehyde and a lesser amount of the alcohol are formed and flashed off along with steam, and the catalyst is recycled. Conversions of over 97 percent are obtained, and the reaction is strongly exothermic. The carbon monoxide and hydrogen are usually in the form of synthesis gas.
When propylene is used as the hydrocarbon, n- and iso-butyraldehyde are formed. This reaction is most frequently run with the C3 and C7 to C12 olefins. When C7 olefins are used, a series of dimethyl- and ethylhexanols and methyl heptanols are formed that are used as octyl alcohols to make plasticizers and esters.