Chemical Properties
A colorless liquid with green onion, herbal, grassy odor. It is used as flavor enhancer and flavoring agent
Chemical Properties
white to light yellow crystal powde
Occurrence
Reported found in raw asparagus, cooked asparagus, kohlrabi, cooked or boiled potatoes, turkey (roasted), raw
chicken, boiled and cooked beef, grilled and roasted beef, pork liver, beer, Finnish whiskey, heated beans, other varieties of mushroom, rice bran, and maize
Uses
2-Acetylthiazole can be used as a flavoring agent in food industries. It may be used as a food additive in the preparation of ′fragrant′ rice.
Uses
2-Acetylthiazole was used in the preparation of triazolothiazoles, chiral alcohols and in aldol condensation reactions.
Definition
ChEBI: 2-Acetylthiazole is an aromatic ketone.
Preparation
By oxidation of the corresponding carbinol using dichromate
Aroma threshold values
Detection at 4 ppb
Taste threshold values
Taste characteristics at 30 ppm: corn chip with slightly musty background
General Description
2-Acetylthiazole is a volatile flavoring substance generally formed by the Maillard reaction between an amino acid and carbonyl compounds. It is reported to occur in canned sweet corn products, cooked pine mushroom, cooked asparagus and roasted beef.
Synthesis
GENERAL STEPS: n-Butyllithium (13.2 mL, 2.5 M hexane solution) was slowly added to anhydrous ether (30 mL) cooled to -78°C under argon protection. Subsequently, an anhydrous ether solution of 2-bromothiazole (2.7 mL) was added dropwise over 20 min. The reaction mixture was continued to be stirred at -78 °C for 30 min. Under rapid stirring, ethyl acetate (5 mL) was added over 2-3 minutes. After addition, the mixture was stirred at -78°C for 30 minutes and then slowly warmed to room temperature. The reaction was quenched with saturated sodium bicarbonate solution (50 mL) and extracted by adding diethyl ether (50 mL) and water (50 mL). The organic phase was separated, washed sequentially with water and saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by fast column chromatography (20% ethyl acetate/petroleum ether) to afford 2-acetylthiazole as a yellow oil (3.3 g, 87% yield).1H NMR (400 MHz, CDCl3) δ: 2.7 (3H, s), 7.65 (1H, s), 8.0 (1H, s); MS (ES+): m/z 128.1 [M+H]+ .
Purification Methods
Check NMR spectrum; if it is not too bad, distil it through an efficient column in a vacuum. The oxime sublimes at 140-145o, m 159o, and when crystallised from H2O has m 163-165.5o. [Erlenmeyer et al. Helv Chim Acta 31 1142 1948, Waisvisz et al. J Am Chem Soc 79 4524 1957, Menasseé et al. Helv Chim Acta 40 554 1957, Beilstein 27 IV 2617.]
References
[1] Patent: WO2004/87699, 2004, A2. Location in patent: Page 82
