2,3-Diethyl-5-methylpyrazine (CAS 18138-04-0) — Sweet Heart Note Fragrance Ingredient
2,3-Diethyl-5-methylpyrazine
CAS 18138-04-0
What Is 2,3-Diethyl-5-methylpyrazine?
2,3-Diethyl-5-methylpyrazine is a synthetic aroma chemical that creates rich, nutty, and roasted coffee-like notes. You’ll encounter it in gourmand fragrances, coffee flavorings, and some savory food products. This molecule matters because it provides authentic roasted character at extremely low concentrations, making it indispensable for creating convincing coffee, chocolate, and nut accords.
Safety Profile
USE WITH AWARENESSWhat Does 2,3-Diethyl-5-methylpyrazine Smell Like?
A powerhouse of roasted depth – imagine espresso beans crackling in a professional roaster, with an initial burst of bitter cocoa nibs that evolves into hazelnut creaminess. The dry-down reveals a lingering toasted bread crust character with subtle earthy undertones. At dilution, it develops surprising caramelized sweetness while maintaining its signature roasted backbone. Exceptionally potent – one drop can dominate a blend.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Provides the dark roasted coffee illusion in this gourmand-oriental, blending with rum and caramel to create a liquored espresso effect.
Forms the coffee-vanilla heart accord, contributing authentic roasted bitterness that contrasts with the sweet floral top notes.
2D Molecular Structure
SMILES: CCC1=C(CC)N=C(C)C=N1
Chemistry, Properties & Perfumer Guide
The Chemistry
This alkylpyrazine belongs to the heterocyclic nitrogen compounds class, structurally featuring two ethyl groups and one methyl group attached to a pyrazine ring. Synthesized through condensation reactions of α-diketones with diamines, its production often involves controlled Maillard-type reactions. The specific substitution pattern creates exceptional odor potency – the 2,3-diethyl configuration is particularly effective for roasted notes. Unlike natural coffee extracts, this synthetic offers superior stability and consistency in formulations.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | ~210 °C (estimated) |
| Flash Point | >100 °C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.01-0.1% | Up to 0.5% | Extremely potent – use sparingly |
| Functional Fragrance | 0.001-0.01% | Up to 0.05% | For coffee fabric softeners |
Classic Accords
Tip: Always pre-dilute to 1% or lower before blending due to overwhelming potency at full strength.
Alternatives & Comparisons
Offers similar roasted character but with more potato-like earthy notes, useful when a less sweet coffee effect is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA standards.
GHS Classification
RIFM Assessment
RIFM evaluation complete – safe at current usage levels with some skin sensitization potential at high concentrations.
Sustainability
As a synthetic material, production avoids agricultural land use but requires petrochemical feedstocks. Recent advances allow production from bio-based precursors, improving its environmental profile. Being highly potent reduces the quantity needed per formulation.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781439856339
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 18138-04-0Physical Properties
| Molecular Weight | 150.22 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.9🔬 PubChem |
| Boiling Point | 183 °C🔬 EPA CompTox |
| Vapor Pressure | 0.1175 mmHg @ 25°C📊 OPERA |
| Flash Point | 80 °C🔬 EPA CompTox |
| Involatility Index | 0.0103💻 Calculated |
| log Kp (skin permeability) | -2.267💻 Calculated |
| SMILES | CCC1=NC=C(N=C1CC)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Slow💻 Calculated |
| Persistence Score | 1.4 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | chocolatehazelnutnuttyroasted• leffingwell |
| Functional Groups | aromatic💻 RDKit |
| 2,3-Diethyl-5-methylpyrazine has a nutty, meaty, roasted hazelnut aroma. -📖 Fenaroli | |
Sensory Thresholds
| Odor Detection Threshold | 0.0001 ppm (n=13)📖 van Gemert |
Regulatory Status
| IOFI Classification | Nature Identical📖 Fenaroli |
Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.
Physicochemical Properties
DTXSID: DTXSID6066317
Physical Properties
| Molecular Weight | 150.225 g/mol🔬 EPA CompTox |
| Density | 0.961 g/cm^3📊 OPERA |
| Boiling Point | 195.866 °C📊 OPERA |
| Melting Point | 33.327 °C📊 OPERA |
| Flash Point | 81.67 °C📊 OPERA |
| Refractive Index | 1.499 Dimensionless📊 OPERA |
| Molar Volume | 157.791 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.95 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 1.903 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.904 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.2 Log10 unitless📊 OPERA |
| Water Solubility | 0.242 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 0.259 mmHg📊 OPERA |
| Viscosity | 3.225 cP📊 OPERA |
| Surface Tension | 34.083 dyn/cm📊 OPERA |
| Thermal Conductivity | 125.631 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 25.78 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 2 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 46.359 cm^3/mol📊 OPERA |
| Polarizability | 18.378 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.
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