Isobutyraldehyde

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 Cannizzaro reaction even though it has alpha hydrogen atom. It is a colorless volatile liquid.

Isobutyraldehyde

Names
Preferred IUPAC name 2-Methylpropanal
Other names 2-Methylpropionaldehyde
Identifiers
CAS Number	78-84-2 Y
3D model (JSmol)	Interactive image
Beilstein Reference	605330
ChEBI	CHEBI:48943 Y
ChemSpider	6313 Y
ECHA InfoCard	100.001.045
EC Number	201-149-6
Gmelin Reference	1658
PubChem CID	6561
RTECS number	NQ4025000
UNII	C42E28168L Y
UN number	2045
CompTox Dashboard (EPA)	DTXSID9021635
InChI InChI=1S/C4H8O/c1-4(2)3-5/h3-4H,1-2H3 Y Key: AMIMRNSIRUDHCM-UHFFFAOYSA-N Y InChI=1/C4H8O/c1-4(2)3-5/h3-4H,1-2H3 Key: AMIMRNSIRUDHCM-UHFFFAOYAE
SMILES CC(C)C=O
Properties
Chemical formula	C4H8O
Molar mass	72.11 g/mol
Appearance	colourless liquid
Odor	Pungent; straw-like
Density	0.79 g/cm3
Melting point	−65 °C (−85 °F; 208 K)
Boiling point	63 °C (145 °F; 336 K)
Solubility in water	moderate
Solubility in other solvents	miscible in organic solvents
Magnetic susceptibility (χ)	−46.38·10−6 cm3/mol
Refractive index (nD)	1.374
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	flammable
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H319
Precautionary statements	P210, P233, P240, P241, P242, P243, P264, P280, P303+P361+P353, P305+P351+P338, P337+P313, P370+P378, P403+P235, P501
Flash point	−19 °C; −2 °F; 254 K
Related compounds
Related alkyl aldehydes	Lilial Hexyl cinnamaldehyde 2-Methylundecanal
Related compounds	Butyraldehyde Propionaldehyde
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Synthesis

Isobutyraldehyde is produced industrially by the hydroformylation of propene. Several million tons are produced annually.^[2]

Biological routes

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]

Other routes

Strong mineral acids catalyse the rearrangement of methallyl alcohol to isobutyraldehyde.

Reactions

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]