{{Lowercase title}} '''γ-Lactones''' are a family of [[organic compound]]s with the formula cyclo-{{chem2|O\dCOCHRCH2CH2}}. The parent member is [[γ-butyrolactone]] (R = H). A commercially important set of γ-lactones are derived from the [[free radical addition]] of [[fatty alcohol]]s and [[acrylic acid]]. They are all weakly volatile liquids, which are colorless when pure, but typical samples are not.<ref name=Ullmann>{{cite book |doi=10.1002/14356007.t11_t02 |chapter=Flavors and Fragrances, 3. Aromatic and Heterocyclic Compounds |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2016 |last1=Panten |first1=Johannes |last2=Surburg |first2=Horst |pages=1–45 |isbn=978-3-527-30673-2 }}</ref>
{| class="wikitable" |+ Some γ-lactone fragrances |- ! Name !! Formula !! [[Registry number]]!!Notes |- | [[γ-Octalactone]] || {{chem2|C8H14O2}} || 104-50-7||fruity |- | [[gamma-Nonalactone|γ-Nonalactone]] || {{chem2|C9H16O2}} || 104-61-0||coconut-like |- | [[γ-Decalactone]] || {{chem2|C10H18O2}} || 706-14-9||peach flavors |- | γ-Undecalactone || {{chem2|C11H20O2}} || 104-67-6||peach flavors |- |[[whisky lactone|β-Methyl-γ-octalactone]]||{{chem2|C9H16O2}}||39212-23-2||whisky lactone |}
==Production== Chemical, biological, and hybrid routes have been developed for these fragrances. Some fungal enzymes hydroxylate fatty acids, leading to the corresponding lactones.<ref>{{cite journal |doi=10.1007/s00253-010-2945-0 |title=Biochemistry of lactone formation in yeast and fungi and its utilisation for the production of flavour and fragrance compounds |date=2011 |last1=Romero-Guido |first1=Cynthia |last2=Belo |first2=Isabel |last3=Ta |first3=Thi Minh Ngoc |last4=Cao-Hoang |first4=Lan |last5=Alchihab |first5=Mohamed |last6=Gomes |first6=Nelma |last7=Thonart |first7=Philippe |last8=Teixeira |first8=Jose A. |last9=Destain |first9=Jacqueline |last10=Waché |first10=Yves |journal=Applied Microbiology and Biotechnology |volume=89 |issue=3 |pages=535–547 |pmid=20981417 }}</ref> In terms of chemical routes, [[fatty alcohol]]s undergo free radical addition to [[acrylic acid]], giving hydroxy carboxylic acids, which spontaneously lactonize.<ref name=Ullmann/> [[File:GammaLactoneFrFattyROH.svg|center|420px|thumb|chemical route to gamma-lactones from fatty alcohols]]
==References== {{reflist}}
== External links == * {{cite journal | last = Poisson | first = L. | title = Characterization of the most odor-active compounds in an American Bourbon whisky by application of the aroma extract dilution analysis. | journal = J Agric Food Chem | volume =56 | issue = 14 | pages = 5813–9 | date = July 23, 2008 | doi =10.1021/jf800382m| pmid = 18570373 }}
{{DEFAULTSORT:Lactone, γ-}} [[Category:Perfume ingredients]] [[Category:Gamma-lactones]]