Isobutyraldehyde is the chemical compound with the formula (CH3)2CHCHO. It is an aldehyde, isomeric with n-butyraldehyde (butanal).[1] Isobutyraldehyde is made, often as a side-product, by the hydroformylation of propene. Its odour is described as that of wet cereal or straw. It undergoes the Cannizaro reaction even though it has alpha hydrogen atom. It is a colorless volatile liquid.
Isobutyraldehyde is produced industrially by the hydroformylation of propene. Several million tons are produced annually.[2]
In the context of butanol fuel, isobutyraldehyde is of interest as a precursor to isobutanol. E. coli as well as several other organisms has been genetically modified to produce isobutanol. α-Ketoisovalerate, derived from oxidative deamination of valine, is prone to decarboxylation to give isobutyraldehyde, which is susceptible to reduction to the alcohol:[3]
(CH3)2CHC(O)CO2H → (CH3)2CHCHO + CO2
(CH3)2CHCHO + NADH + H+ → (CH3)2CHCH2OH + NAD+
It can also be produced using engineered bacteria.[4]
Strong mineral acids catalyse the rearrangement of methallyl alcohol to isobutyraldehyde.
Hydrogenation of the aldehyde gives isobutanol. Oxidation gives methacrolein or methacrylic acid. Condensation with formaldehyde gives hydroxypivaldehyde.[2] The latter is a precursor to vitamin B5.[5]