CH2CHCHO

CH2CHCHO, commonly written to denote acrolein, is the simplest α,β-unsaturated aldehyde. Its structure is CH2=CH-CHO, and its molecular formula is C3H4O. It is a colorless to slightly yellow liquid with a strong, acrid odor. It is highly reactive, especially toward nucleophiles, due to conjugation between the carbon–carbon double bond and the aldehyde carbonyl. It polymerizes readily and is usually stabilized with inhibitors when handled.

Production and occurrence: Acrolein is produced industrially by catalytic oxidation of propylene in the presence of air over metal oxide catalysts, yielding acrolein which can be further oxidized to acrylic acid. It can also be generated from glycerol oxidation, a byproduct of biodiesel production, under controlled conditions.

Reactions and uses: As an α,β-unsaturated aldehyde, acrolein is a versatile electrophile that participates in Michael additions and aldol-type condensations. It serves as an important industrial intermediate for the manufacture of acrylic esters and plastics; the oxidation of acrolein yields acrylic acid, an essential monomer for polyacrylates. It is also used as a biocide and herbicide in some applications, and as a chemical building block in various specialty syntheses.

Safety: Acrolein is highly toxic, a strong eye and respiratory irritant, and a potential carcinogen. It is flammable and reacts with air and moisture. Handling requires appropriate engineering controls and personal protective equipment; storage typically involves stabilizers to prevent polymerization.

See also: allyl alcohol, acrylic acid, propenal, aldehydes.