{{chembox | Watchedfields = changed | verifiedrevid = 477213431 | ImageFileL1 = Furan-2-one.svg | ImageSizeL1 = 120 | ImageAltL1 = Skeletal formula of 2-furanone | ImageFileR1 = 2-Furanone-3D-balls.png | ImageSizeR1 = 130 | ImageAltR1 = Ball-and-stick model of the 2-furanone molecule | PIN = Furan-2(5''H'')-one | OtherNames = Furan-2-one, γ-crotonolactone, butenolide, 5''H''-furan-2-one | Section1 = {{Chembox Identifiers | Beilstein = 383585 | Gmelin = 773828 | KEGG_Ref = {{keggcite|correct|kegg}} | KEGG = C17601 | InChI = 1/C4H4O2/c5-4-2-1-3-6-4/h1-2H,3H2 | InChIKey = VIHAEDVKXSOUAT-UHFFFAOYAD | ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL = 166223 | EC_number = 207-839-3 | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C4H4O2/c5-4-2-1-3-6-4/h1-2H,3H2 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = VIHAEDVKXSOUAT-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 497-23-4 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 8KXK25H388 | PubChem = 10341 | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 38118 | SMILES = O=C\1OC/C=C/1 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 9917 | MeSHName = butenolide }} | Section2 = {{Chembox Properties | Formula = C<sub>4</sub>H<sub>4</sub>O<sub>2</sub> | MolarMass = 84.07336 | Appearance = | Density = 1.185 g/cm<sup>3</sup>, liquid | MeltingPtC = 4 to 5 | MeltingPt_ref=<ref name="Sigma">Sigma-Aldrich Chemicals [http://www.sigmaaldrich.com/catalog/search/ProductDetail/ALDRICH/283754 Product detail]</ref> | BoilingPtC = 86 to 87 | BoilingPt_notes= 12 mm&nbsp;Hg<ref name="Sigma"/> | Solubility = }} | Section7 = {{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }}

'''2-Furanone''' is a [[heterocycle|heterocyclic]] [[organic compound]]. It is also known as '''γ-crotonolactone''' ('''GCL'''), as it is formally the [[lactone]] derived from γ-hydroxy[[isocrotonic acid]]. The chemical is colloquially called "butenolide", and is the parent structure for the [[butenolide]] class of compounds. It is a colourless liquid.

==Synthesis and reactions== 2-Furanone is prepared by oxidation of [[furfural]]:<ref>{{cite journal|last1=Näsman|first1=Jan H.|title=3-Methyl-2(5''H'')-furanone|journal=Organic Syntheses|date=1990|volume=68|page=162|doi=10.15227/orgsyn.068.0162}}</ref>

:[[File:Synthesis 2-Furanone.svg|400px]]

It exists in equilibrium with the [[tautomer]] 2-hydroxy[[furan]], which serves as an intermediate in the interconversion between the β- and α-furanones.{{explain|reason=What are the alpha and beta forms?|date=October 2017}} The β form is the more stable. The interconversion is catalyzed by [[base (chemistry)|base]].

2-Furanones can be converted to [[furan]]s by a two-step process of [[redox reaction|reduction]] followed by [[dehydration reaction]].

Furanone is thought to contribute to the unique taste of [[maple syrup]].

==See also== * [[:Category:Furanones]], various substituted structural analogs * [[Pyrone]], which has one more carbon atom in the ring

==References== {{Reflist}}

{{GHBergics}}

{{DEFAULTSORT:Furanone, 2-}} [[Category:Furanones]] [[Category:GHB receptor ligands]]