4,5-Dimethylthiazole

CAS NO.：3581-91-7
Empirical Formula: C5H7NS
Molecular Weight: 113.18
MDL number: MFCD00005336
EINECS: 222-703-3
SAFETY DATA SHEET (SDS)
Update Date: 2026-04-03 14:17:14

What is 4,5-Dimethylthiazole?

Chemical properties

4,5-Dimethylthiazole is a colorless to light yellow liquid that has a roasted nutty, meaty, boiled poultry-like odor.

Occurrence

Reported found in peanuts, toasted oats, malt, peach, pork, coffee, krill, shrimp and scallops

The Uses of 4,5-Dimethylthiazole

4,5-Dimethylthiazole was used in the preparation of 4-(bromomethyl)-5-(dibromomethyl)thiazole.

Preparation

From methyl-α-bromoethyl ketone; by oxidation of 2-mercaptothiazoles with hydrogen peroxide in aqueous solution; from 2-mercapto-4,5-dimethylthiazole.

Definition

ChEBI: 4,5-Dimethylthiazole is a member of thiazoles.

Aroma threshold values

Detection: 470 ppb

Taste threshold values

Taste characteristics at 5 ppm: fishy, amine and pyridine-like with shrimp and savory nuances

Synthesis Reference(s)

The Journal of Organic Chemistry, 6, p. 764, 1941 DOI: 10.1021/jo01205a011

General Description

4,5-Dimethylthiazole is a thiazoles compounds that containing a thiazole ring substituted at positions 4 and 5 only. Radical bromination of 4,5-dimethylthiazole using N-bromosuccinimide in the presence of 2,2′-azobisisobutyronitrile yields mono-, tri- and tetrabromo compounds.

Properties of 4,5-Dimethylthiazole

Melting point:	83-84 C
Boiling point:	158 °C/742 mmHg (lit.)
Density	1.07 g/mL at 25 °C (lit.)
refractive index	n20/D 1.521(lit.)
FEMA	3274 \| 4,5-DIMETHYLTHIAZOLE
Flash point:	124 °F
storage temp.	Sealed in dry,Room Temperature
form	solid
pka	pK1:3.73 (25°C,μ=0.1)
Specific Gravity	1.070
Odor	at 0.10 % in dipropylene glycol. roasted nutty fishy green boiled shrimp
JECFA Number	1035
BRN	105694
CAS DataBase Reference	3581-91-7(CAS DataBase Reference)
NIST Chemistry Reference	Thiazole, 4,5-dimethyl-(3581-91-7)

Safety information for 4,5-Dimethylthiazole

Signal word	Danger
Pictogram(s)	Flame Flammables GHS02 Corrosion Corrosives GHS05 Exclamation Mark Irritant GHS07
GHS Hazard Statements	H226:Flammable liquids H302:Acute toxicity,oral H315:Skin corrosion/irritation H318:Serious eye damage/eye irritation H335:Specific target organ toxicity, single exposure;Respiratory tract irritation
Precautionary Statement Codes	P210:Keep away from heat/sparks/open flames/hot surfaces. — No smoking. P233:Keep container tightly closed. P280:Wear protective gloves/protective clothing/eye protection/face protection. P301+P312:IF SWALLOWED: call a POISON CENTER or doctor/physician IF you feel unwell. P303+P361+P353:IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower. P305+P351+P338:IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.