Crotonaldehyde

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. It is a Michael acceptor. Addition of methylmagnesium chloride affords 3-penten-2-ol.

Safety
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.