Chemical Properties
Colorless clear liquid. Very slight Iy soluble in water, soluble in alcohol and oils. Powerful, fresh-fruity-oily, siightly green
odor. Fresh-fruity, light and powerfu), penetrating taste.
Chemical Properties
Ethyl 3-hydroxyhexanoate has a fruity odor.
Occurrence
Reported found in citrus, grape, orange, grapefruit and tangerine juice, orange peel oil, pineapple, strawberry,
cognac, Scotch whiskey, red and white wine, passion fruit, mango, quince, wood apple, mountain papaya, pawpaw and hog plum
(Spondias mombins L.).
Uses
Ethyl 3-Hydroxyhexanoate is a general volatile organic compound which contributes to the scent and flavor profile of various fruits such as guava fruit and bananas.
Preparation
By esterification of bera-Hydroxy
caproic acid, which is an isomer of Leucic
acid. The acid can be obtained from Butyraldchyde by condensation with Bromo acetic
ester in presence of Zinc catalyst.
Definition
ChEBI: A fatty acid ester that is the ethyl ester of 3-hydroxyhexanoic acid.
Taste threshold values
Taste characteristics at 80 ppm: sweet, fruity, grape with citrus notes.
Synthesis Reference(s)
The Journal of Organic Chemistry, 39, p. 269, 1974
DOI: 10.1021/jo00916a043
Synthesis
GENERAL STEPS: THF (200 mL) was added to a 500 mL round-bottomed flask pre-dried in an oven equipped with a 30 cm long condenser and kept open to the atmosphere.THF was used directly without further drying or purification. Subsequently, it was heated to reflux temperature (66°C) on a sand bath and the solvent was rapidly stirred using a magnetic stir bar. The condenser was temporarily raised and 6.5 g (0.1 mol, 2 eq.) of ZnO particles were added to the hot solvent. Next, n-butyraldehyde (0.1 mol) and ethyl bromoacetate (0.2 mol, 2 eq.) were added to the reaction mixture. The condenser was immediately reconnected to the round-bottom flask, at which point rapid boiling was observed. After allowing the reaction to reflux rapidly for 1 min, the reaction vessel was removed from the heat source and cooled to room temperature. For all substrates, the reaction was monitored by TLC (eluent: hexane-EtOAc, 80:20) within 20 minutes to confirm completion. Excess THF was removed under vacuum, and the brown oil obtained was dissolved in hexane and the reaction quenched with H2O to form a yellow precipitate. After filtering the mixture, the hexane layer was washed sequentially with H2O (100 mL), 1M HCl (2 × 50 mL), H2O (100 mL) and brine (50 mL), and then dried with Na2SO4. Finally, hexane was removed under vacuum to afford the target product ethyl 3-hydroxyhexanoate in 86% to 95% yield (see Table 1).
References
[1] Synthetic Communications, 2001, vol. 31, # 24, p. 3781 - 3789
[2] Journal of Organic Chemistry, 1982, vol. 47, # 25, p. 5030 - 5032
[3] Synthesis (Germany), 2015, vol. 47, # 1, p. 79 - 82
[4] Organic Letters, 2003, vol. 5, # 20, p. 3615 - 3617
