Editing Lactone (section)

==Nomenclature==
[[Greek alphabet#Letters|Greek prefix]]es in alphabetical order indicate ring size.

{| class="wikitable skin-invert"
! Ring size<br />(number of atoms<br/> in the ring)
! {{nobr|[[Systematic name]]}}
! [[IUPAC name]]
! Parent lactone
! Structure, comment
|-
|3
|[[α-lactone]]
|Oxiran-2-one
|[[Acetolactone]]
|[[File:Acetolactone-2D-skeletal.png|left|frameless|120x120px]]
|-
|4
|[[β-lactone]]
|Oxetan-2-one
|{{ubl|β-Propiolactone|Propiolactone}}
|[[File:Propiolactone.png|100px]]

|-
|5
|[[γ-lactone]]
|Oxolan-2-one
|γ-Butyrolactone
|[[File:GBL chemical structure.svg|100px]]

|-
|6
|[[δ-lactone]]
|Oxan-2-one
|{{ubl|[[δ-Valerolactone]]}}
|[[file:delta-valerolactone.png|100px]]
|-
|7
|[[ε-lactone]]
|Oxepan-2-one
|{{ubl|ε-Caprolactone|Caprolactone|Hexanolide}}
|[[File:Caprolactone.png|85px]]
|}

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, δ-lactone = 6-membered, etc. {{anchor|macrolactone}}[[Macrocyclic]] lactones are known as '''macrolactones'''.<ref>{{cite web|url=http://www.chem.ucla.edu/~harding/IGOC/M/macrolactone.html|title=Illustrated Glossary of Organic Chemistry|author=Steven A. Hardinger|publisher=Department of Chemistry & Biochemistry, [[University of California, Los Angeles|UCLA]]}}</ref>{{wiktionary|macrolactone}}

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 name]]s, 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.<ref>{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = [[Royal Society of Chemistry|The Royal Society of Chemistry]] | date = 2014 | location = Cambridge | page = 822 | doi = 10.1039/9781849733069-00648 | isbn = 978-0-85404-182-4}}</ref>