2propenal

2-propenal, commonly known as acrolein, is the simplest α,β-unsaturated aldehyde. Its structure is CH2=CH-CHO, a vinyl group conjugated with a formyl group. It is a colorless to pale yellow liquid with a very strong, acrid odor. The conjugated enal system makes acrolein highly reactive as a Michael acceptor and as a general electrophile; it readily participates in additions to nucleophiles, oxidation, and polymerization. In storage it is often stabilized with inhibitors to prevent unwanted polymerization.

Production and occurrence: Acrolein is produced industrially mainly by catalytic oxidation of propylene in the presence of oxygen, typically as an intermediate in the production of acrylic acid and acrylate esters. Alternative routes include dehydration or oxidation of glycerol under specialized conditions. It can also be generated as a byproduct in some oxidation processes. Commercial samples are usually stabilized with polymerization inhibitors.

Applications: The principal use of acrolein is as a chemical intermediate in the manufacture of acrylic acid, acrylates, and related polymers. It serves as a versatile building block for resins, coatings, and specialty chemicals. Its reactivity also enables synthesis of diverse derivatives, though handling is constrained by safety concerns.

Safety and handling: Acrolein is highly toxic and a potent eye and respiratory irritant. It is a lachrymator and poses significant health hazards upon inhalation, ingestion, or skin exposure. It reacts with oxidizers and reductants and can polymerize vigorously if not stabilized. Proper handling requires engineering controls, protective equipment, and storage with appropriate inhibitors to prevent polymerization.

See also: related α,β-unsaturated aldehydes such as methacrolein.