γ-Lactone

γ-Lactones are a family of organic compounds with the formula cyclo-O=COCHRCH₂CH₂. The parent member is 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

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

External links

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.

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