2-Ethyl-4-methylthiazole (CAS 15679-12-6) — Spicy Middle Note Fragrance Ingredient
2-Ethyl-4-methylthiazole
CAS 15679-12-6
What Is 2-Ethyl-4-methylthiazole?
2-Ethyl-4-methylthiazole is a synthetic aroma chemical used to create savory, roasted notes in fragrances and flavors. You’ll encounter it in gourmand perfumes and some food flavorings. This molecule matters because it adds realistic meaty or nutty nuances that are hard to achieve naturally, making it valuable for creating complex savory accords in modern perfumery.
Safety Profile
USE WITH AWARENESSWhat Does 2-Ethyl-4-methylthiazole Smell Like?
2-Ethyl-4-methylthiazole bursts with an intensely savory, roasted character reminiscent of seared meat and toasted nuts. The initial impression is powerfully umami, like the crust on a perfectly grilled steak. As it evolves, it reveals earthy, slightly sulfurous undertones that recall roasted coffee beans or fried onions. In drydown, it leaves a lingering, warm, almost brothy quality that blends beautifully with woody and spicy notes. Its tenacity is moderate, making it useful for creating savory heart notes that persist without overwhelming.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used sparingly to enhance the leather’s natural animalic character, adding depth to the suede accord.
Provides subtle savory contrast to the bright citrus opening and warm woody base.
2D Molecular Structure
SMILES: CCC1=NC(C)=CS1
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Ethyl-4-methylthiazole belongs to the thiazole class of heterocyclic compounds, characterized by a five-membered ring containing both sulfur and nitrogen atoms. While thiazoles occur naturally in some roasted foods, this specific compound is synthesized for perfumery use. Common synthetic routes involve the reaction of α-haloketones with thioamides. The ethyl and methyl substitutions at positions 2 and 4 respectively create its distinctive odor profile.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Odor Threshold | Extremely low (ppb range) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Used sparingly for savory effects |
| Functional Fragrance | 0.01-0.1% | Up to 0.5% | Masking agent in some products |
Classic Accords
Tip: Use in trace amounts (0.1% or less) to avoid overwhelming compositions with meaty notes.
Alternatives & Comparisons
More green, tomato leaf character compared to the roasted quality of 2-ethyl-4-methylthiazole.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA. No specific usage limits established.
RIFM Assessment
No comprehensive RIFM evaluation published as of 2023.
Sustainability
As a synthetic material, 2-ethyl-4-methylthiazole has minimal environmental impact in production compared to natural extracts requiring agricultural land use. Its potency means very small quantities are needed, reducing overall material consumption in formulations.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID6065923
Physical Properties
| Molecular Weight | 127.21 g/mol🔬 EPA CompTox |
| Density | 1.054 g/cm^3📊 OPERA |
| Boiling Point | 161.5 °C🔬 EPA CTX |
| Melting Point | -14.288 °C📊 OPERA |
| Flash Point | 54.21 °C📊 OPERA |
| Refractive Index | 1.524 Dimensionless📊 OPERA |
| Molar Volume | 121.229 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.751 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 1.733 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.751 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.56 Log10 unitless📊 OPERA |
| Water Solubility | 0.532 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 4.636 mmHg📊 OPERA |
| Viscosity | 2.582 cP📊 OPERA |
| Surface Tension | 33.993 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 12.89 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 1 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 37.103 cm^3/mol📊 OPERA |
| Polarizability | 14.709 Å^3📊 OPERA |
Data Sources:
🔬 EPA Experimental data from U.S. EPA CompTox Chemicals Dashboard & CTX APIs. 📊 OPERA Predicted using EPA's OPERA QSAR models. 💻 Computed Calculated from SMILES using RDKit.
