Page 175 - Chemical and process design handbook

Speight_Part II_B 11/7/01 3:11 PM Page 2.116

n-BUTYRALDEHYDE

o
n-butyraldehyde (boiling point: 74.8 C, density: 0.8016) is made by the
reaction of propylene (propene-1, CH CH=CH ), carbon monoxide, and
3 2
o
hydrogen (synthesis gas) at 130 to 175 C and 3675 psi (25.3 MPa) over
a rhodium carbonyl, cobalt carbonyl, or ruthenium carbonyl catalyst
(Fig. 1).
CH CH=CH + CO + H → CH CH CH CH=O
3 2 2 3 2 2
The reaction is referred to as the oxo process, and a second product of
o
the reaction is iso-butyraldehyde (boiling point: 64.1 C, density: 0.7891).
CH CH=CH + CO + H2 → CH CH(CH )CH=O
3 2 3 3
The ratio of the normal to the iso product is approximately 4:1. Other
catalysts produce different normal-to-iso product ratios under different
conditions. For example, a rhodium catalyst can be used at lower temper-
atures and pressures and gives a normal-to-iso product ratio of approxi-
mately 16:1.
Butyraldehyde is used for the production of n-butyl alcohol.

CH CH CH CH=O + H → CH CH CH CH OH
3 2 2 2 3 2 2 2

See Oxo Reaction, Synthesis Gas.

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