29926-41-8

Basic information

• Product Name: 2-Acetyl-2-thiazoline
• Synonyms: 2-ACETYL-2-THIAZOLINE;1-(4,5-DIHYDRO-THIAZOL-2-YL)-ETHANONE;FEMA NUMBER 3817;FEMA 3817;1-(4,5-Dihydro-1,3-thiazol-2-yl)ethanone;1-(4,5-dihydro-2-thiazolyl)-ethanon;2-acetylthiazoline;2-Thiazoline, 2-acetyl
• CAS NO: 29926-41-8
• Molecular Formula: C₅H₇NOS
• Molecular Weight: 129.18
• Product Categories: ACETYLGROUP;Aroma Chemicals;thiazole Flavor
• Mol File: 29926-41-8.mol
• Article Data: 3

Chemical Properties

• Melting Point: 26-30 °C(lit.)
• Boiling Point: 223.8 °C at 760 mmHg
• Flash Point: 198 °F
• Appearance: /
• Density: 1.17 g/mL at 25 °C(lit.)
• Vapor Pressure: 0.0942mmHg at 25°C
• Refractive Index: n20/D 1.5305(lit.)
• Storage Temp.: 2-8°C
• Solubility: soluble in Methanol
• PKA: 1.45±0.10(Predicted)
• CAS DataBase Reference: 2-Acetyl-2-thiazoline(CAS DataBase Reference)
• NIST Chemistry Reference: 2-Acetyl-2-thiazoline(29926-41-8)
• EPA Substance Registry System: 2-Acetyl-2-thiazoline(29926-41-8)

Safety Data

• Hazard Codes: Xn
• Statements: 22-36
• Safety Statements: 26
• RIDADR: UN 2811 6.1/PG 3
• WGK Germany: 3
• Hazardous Substances Data: 29926-41-8(Hazardous Substances Data)

Usage

Identification

▼▲ CAS.No.:? 29926-41-8? FL.No.:? 15.01 FEMA.No.:? 3817 NAS.No.:? .n/a? CoE.No.:? 2335 EINECS.No.:? n/a? JECFA.No.:? 1759

Description

May contain ~1% acetic acid. Organoleptic characteristics: green onion, herbal, grassy.

Regulatory Status

CoE: n/a FDA: n/a FDA Rx: n/a JECFA: ADI: Acceptable. No safety concern at current levels of intake when used as a flavoring agent (2007).

Usage

Reported uses (ppm): (FEMA, 1994) ▼▲ Food Category? Usual? Max.? Baked goods? 0.02 0.2 Breakfast cereals? 0.01 0.1 Chewing gum? 0.05 0.5 Confection, frosting? 0.01 0.1 Fats, oils? 0.01 0.1 Fish products? 0.02 0.2 Gravies? 0.02 0.2 Hard candy? 0.01 0.1 Meat products? 0.02 0.2 Other grains? 0.01 0.1 Poultry? 0.02 0.2 Snack foods? 0.05 0.5 Soft candy? 0.01 0.1 Soups? 0.02 0.2

Natural occurrence

Reported present in beef (boiled, grilled, roasted), chicken (raw), corn (sweet).

Chemical Properties

May contain ~1% acetic acid. Organoleptic characteristics: green onion, herbal, grassy

Occurrence

Reported present in beef (boiled, grilled, roasted), chicken (raw), corn (sweet).

InChI:InChI=1/C5H7NOS/c1-4(7)5-6-2-3-8-5/h2-3H2,1H3

Synthetic route

2-acetyl-1,3-thiazolidine (67399-73-9) → 1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8)

Conditions	Yield
With tert.-butylhydroperoxide; ruthenium trichloride; N,N,N,N,-tetramethylethylenediamine In acetonitrile at 20℃; for 4h; Catalytic oxidation;	70%

2-ethyl-2-thiazoline (16982-46-0) → 1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8)

Conditions	Yield
Stage #1: 2-ethyl-2-thiazoline With tert.-butylhydroperoxide; selenium(IV) oxide In dichloromethane at 20℃; for 3h; Stage #2: With triphenylphosphine In dichloromethane at 0℃; for 12h;	40%

2-(1-hydroxyethyl)-4,5-dihydrothiazole → 1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8)

Conditions	Yield
In water at 100℃; for 0.166667h; Thermodynamic data; Product distribution; E(a); var. temp., time and pH;

2-mercaptoethylamine hydrochloride (156-57-0) + 2-oxopropanal (78-98-8) → 1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8)

Conditions	Yield
With potassium phosphate buffer; sodium at 6℃; for 18h; Mechanism;

1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8) → [1-(4,5-Dihydro-thiazol-2-yl)-eth-(E)-ylidene]-hydrazine

Conditions	Yield
With hydrazine hydrate In ethanol Condensation; Heating;	72%

1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8) + N,N-dimethyl-formamide dimethyl acetal (4637-24-5) → (E)-1-(4,5-dihydrothiazol-2-yl)-3-(dimethylamino)prop-2-en-1-one (1233858-23-5)

Conditions	Yield
at 160℃; for 0.333333h; Microwave irradiation;	64%

1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8) + thiosemicarbazide (79-19-6) → 2-acetyl-2-thiazoline thiosemicarbazone

Conditions	Yield
With acetic acid In acetonitrile for 2h; Reflux;	52%

1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8) + dimethyl acetylenedicarboxylate (762-42-5) → dimethyl 6-methyl-5-oxo-2,3,5,7a-tetrahydropyrrolo[2,1-b]thiazole-7,7a-dicarboxylate (1233858-39-3)

Conditions	Yield
In acetonitrile at 60℃; for 0.25h; Microwave irradiation;	19%

1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8) → 3-methyl-5,6-dihydro-thiazolo[3,2-c][1,2,3]triazole

Conditions	Yield
Multi-step reaction with 2 steps 1: 72 percent / hydrazine hydrate / ethanol / Heating 2: 88 percent / PhI(OAc)2 / CH2Cl2 / 0.5 h / 20 °C View Scheme

1-(4,5-dihydro-1,3-thiazol-2-yl)ethanone (29926-41-8) + ethyl 2-(4-hydrazinophenyl)-2-methylpropanoate (192643-90-6) → ethyl 2-methyl-2-(2-(1,3-thiazol-2-yl)-1H-indol-5-yl)propanoate (1076220-44-4)

Conditions	Yield
With acetic acid; zinc(II) chloride In ethanol

Upstream product

• 16982-46-0 2-ethyl-2-thiazoline 
• 67399-73-9 2-acetyl-1,3-thiazolidine 
• 156-57-0 2-mercaptoethylamine hydrochloride 
• 78-98-8 2-oxopropanal 

Relevant articles and documents

Studies on the Formation and Stability of the Roast-Flavor Compound 2-Acetyl-2-thiazoline

2-(1-Hydroxyethyl)-4,5-dihydrothiazole (HDT) was identified by 1H- and 13C-NMR measurements as the main volatile product formed by storage of an aqueous solution of cysteamine and methylglyoxal at low temperatures (6 deg C).The structure of HDT was confirmed by synthesis.Systematic studies on the thermal stability of the HDT under different conditions either in aqueous solution or during high-resolution gas chromatography revealed that HDT is an important intermediate in the formation of the intensely roasty smelling food flavor compound 2-acetyl-2-thiazoline (AT).Model studies showed that more than 10percent of the precursor HDT was converted into AT simply by heating for 10 min in water.The activation energy of this reaction was 57.4 kJ/mol.Experiments on the thermal stability of AT itself revealed that heating in aqueous solution also led to a degradation of AT, whereas heating in an oil significantly stabilized the flavor compound. - Keywords: 2-(1-Hydroxyethyl)-4,5-dihydrothiazole; 2-acetyl-2-thiazoline; flavor precursor; stable isotope dilution analysis.

Novel synthesis of 2-thiazolines

The synthesis of a series of 2-thiazolines was carried out under mild conditions from the corresponding thiazolidines, by a Ru-catalyzed/TBHP oxidation reaction conditions. The reaction was chemoselective towards the amine-imine oxidation and was also regioselective, affording the unsaturation at the 2-position of the heterocycle, even with thiazolidine substrates bearing ester groups at the 4-position. (C) 2000 Elsevier Science Ltd.