page_title: Lactone
section_title: Nomenclature
hierarchical_section_title: Lactone / Nomenclature
caption_attribution_description: English: Different types of lactones (alpha, beta, gamma, delta) Deutsch: Verschiedene Typen von Lactonen (alpha, beta, gamma, delta)
context_page_description: Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure, or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring.
  Lactones are formed by intramolecular esterification of the corresponding hydroxycarboxylic acids, which takes place spontaneously when the ring that is formed is five- or six-membered. Lactones with three- or four-membered rings are very reactive, making their isolation difficult. Special methods are normally required for the laboratory synthesis of small-ring lactones as well as those that contain rings larger than six-membered.
context_section_description: Lactones are usually named according to the precursor acid molecule (aceto = 2 carbon atoms, propio = 3, butyro = 4, valero = 5, capro = 6, etc.), with a -lactone suffix and a Greek letter prefix that specifies the number of carbon atoms in the heterocycle — that is, the distance between the relevant -OH and the -COOH groups along said backbone. The first carbon atom after the carbon in the -COOH group on the parent compound is labelled α, the second will be labeled β, and so forth. Therefore, the prefixes also indicate the size of the lactone ring: α-lactone = 3-membered ring, β-lactone = 4-membered, γ-lactone = 5-membered, etc. Macrocyclic lactones are known as macrolactones.
  The other suffix used to denote a lactone is -olide, used in substance class names like butenolide, macrolide, cardenolide or bufadienolide.
  To obtain the preferred IUPAC names, lactones are named as heterocyclic pseudoketones by adding the suffix ‘one’, ‘dione’, ‘thione’, etc. and the appropriate multiplicative prefixes to the name of the heterocyclic parent hydride.
caption: Lactone nomenclature: α-acetolactone, β-propiolactone, γ-butyrolactone, and δ-valerolactone
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