2-hydroxy gamma-lactones

Gamma-lactones are quite prevalent in biolipids and in microbiological transformation products. Any of these may be the source of y-lactones. Hydroxy-acids and unsaturated acids may also be the source of y-lactones in Aleksinac shale. If y-lactones were found to be typical for certain class of sediments, they might shed more light on the source of the organic matter of these sediments. 

The acid catalyzed conversion of gamma-hydroxy-butyric acid into its lactone was studied In 0.2 N HC1 solution at 25 C. The initial concentration of the acid was 18.23 in arbitrary units. The lactone concentration was... 

These terpene notes are supported by (Z)-3-hexenol, (E)-2-hexenal, (E)-2-hexenol with their fresh, green character. Gamma- and delta-lactones (4-decanolide, 5-decan-olide, 4-dodecanolide, 5-dodecanolide-(Z)-7-decen-5-olide) impart the sweet, creamy, buttery, peach and apricot character. 2,5-Dimethyl-4-hydroxy-furan-3(2H)-one and 2,5-dimethyl-4-methoxy-furan-3(2H)-one are responsible for the sweet creamy fruity body. A bouquet of esters imparts the overall fruity character (mainly esters of ethyl-, (Z)-3-hexenyl and butyl alcohol with acetic-, butanoic-, 2-butenoic, 3-hydroxybutanoic- and hexanoic acid). 

A reaction analogous with that of cyclic-anhydride-formation is the formation of lactones from 7-hydroxy acids and from 7-halogen acids. (Cf. page 39.) A related reaction is the dehydration of acids possessing a carbonyl group in the gamma position. 

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