An enone, also called an α,β-unsaturated carbonyl, is a type of organic compound consisting of an alkene conjugated to a ketone. The simplest enone is methyl vinyl ketone (butenone) or CH2=CHCOCH3. An enal is the corresponding α,β-unsaturated aldehyde, an example being acrolein (CH2=CHCHO).
Enones are typically producing using an Aldol condensation or Knoevenagel condensation. Some commercially significant enones are produced by condensations of acetone, e.g. mesityl oxide and isophorone.
Enones undergo many kinds of reactions.
They are electrophilic both at the carbonyl carbon but also at the β-carbon. Depending on conditions, either site is attacked by nucleophiles. Addition to the alkene is called conjugate additions. Michael additions are examples.
Enones are often good dienophiles in Diels-Alder reactions. They are activated by Lewis acids, which bind to the carbonyl oxygen.
Enones are readily reduced. They can undergo both reduction of the carbonyl and of the alkene (conjugate reduction), as well as both.
Sterically unhindered enones such as methyl vinyl ketone are prone to polymerization.
- Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, ISBN 0-471-72091-7
- Hardo Siegel, Manfred Eggersdorfer "Ketones" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim.doi:10.1002/14356007.a15_077