γ-Lactones are a family of organic compounds with the formula cyclo-O=COCHRCH2CH2. The parent member is γ-butyrolactone (R = H). A commercially important set of γ-lactones are derived from the free radical addition of fatty alcohols and acrylic acid. They are all weakly volatile liquids, which are colorless when pure, but typical samples are not.[1]

Some γ-lactone fragrances
Name Formula Registry number Notes
γ-Octalactone C8H14O2 104-50-7 fruity
γ-Nonalactone C9H16O2 104-61-0 coconut-like
γ-Decalactone C10H18O2 706-14-9 peach flavors
γ-Undecalactone C11H20O2 104-67-6 peach flavors
β-Methyl-γ-octalactone C9H16O2 39212-23-2 whisky lactone

Production

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Chemical, biological, and hybrid routes have been developed for these fragrances. Some fungal enzymes hydroxylate fatty acids, leading to the corresponding lactones.[2] In terms of chemical routes, fatty alcohols undergo free radical addition to acrylic acid, giving hydroxy carboxylic acids, which spontaneously lactonize.[1]

 
chemical route to gamma-lactones from fatty alcohols

References

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  1. ^ a b Panten, Johannes; Surburg, Horst (2016). "Flavors and Fragrances, 3. Aromatic and Heterocyclic Compounds". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–45. doi:10.1002/14356007.t11_t02. ISBN 978-3-527-30673-2.
  2. ^ Romero-Guido, Cynthia; Belo, Isabel; Ta, Thi Minh Ngoc; Cao-Hoang, Lan; Alchihab, Mohamed; Gomes, Nelma; Thonart, Philippe; Teixeira, Jose A.; Destain, Jacqueline; Waché, Yves (2011). "Biochemistry of lactone formation in yeast and fungi and its utilisation for the production of flavour and fragrance compounds". Applied Microbiology and Biotechnology. 89 (3): 535–547. doi:10.1007/s00253-010-2945-0. PMID 20981417.
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  • Poisson, L. (July 23, 2008). "Characterization of the most odor-active compounds in an American Bourbon whisky by application of the aroma extract dilution analysis". J Agric Food Chem. 56 (14): 5813–9. doi:10.1021/jf800382m. PMID 18570373.