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Template:Chembox E numberTemplate:Chembox SolubilityInWater
IUPAC name (E)-2-Butenal
Other names Crotonaldehyde
crotoinic aldehyde
Molecular formula C4H6O
3D model (JSmol)
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Molar mass 70.09 g/mol
Density 0.846 g/cm3
Melting point
Boiling point
Refractive index (nD) 1.4362
R-phrases 11-24/25-26-37/38-41-48/22-50-68
S-phrases 26-28-36/37/39-45-61
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Crotonaldehyde is a chemical compound with the formula CH3CH=CHCHO. The compound exists as two isomers, E- and Z- depending on the relative position of the methyl (CH3) and formyl (CHO) groups. The E-isomer is more common (data given in Table is for the E-isomer). This lachrymatory liquid is moderately soluble in water and miscible in organic solvents. As an unsaturated aldehyde, crotonaldehyde is a versatile intermediate in organic synthesis.

Applications in organic synthesis

The compound exhibits diverse reactivity. It is an excellent prochiral dienophile.[1] It is a Michael acceptor. Addition of methylmagnesium chloride affords 3-penten-2-ol.[2]


Crotonaldehyde is an irritant. It is listed as an "extremely hazardous substance" as defined by the U.S. Emergency Planning and Community Right-to-Know Act.

See also


  1. Longley, Jr., R. I..; Emerson, W. S.; Blardinelli, A. J. (1963). "3,4-Dihydro-2-methoxy-4-methyl-2H-pyran". Org. Synth.; Coll. Vol. 4: 311. 
  2. Coburn, E. R. (1955). "3-Penten-2-ol". Org. Synth.; Coll. Vol. 3: 696.