2-Methoxy-3-(1-methylpropyl)pyrazine (CAS 24168-70-5) — Green Top-Middle Note Fragrance Ingredient
2-Methoxy-3-(1-methylpropyl)pyrazine
CAS 24168-70-5
What Is 2-Methoxy-3-(1-methylpropyl)pyrazine?
2-Methoxy-3-(1-methylpropyl)pyrazine is a synthetic aroma chemical that adds a green, bell pepper-like nuance to fragrances. You’ll encounter it in fresh, vegetal perfumes and some gourmand scents. This pyrazine compound matters because it provides an ultra-realistic green pepper note at extremely low concentrations, allowing perfumers to create photorealistic vegetable garden accords or add a crisp edge to fruity compositions.
Safety Profile
USE WITH AWARENESSWhat Does 2-Methoxy-3-(1-methylpropyl)pyrazine Smell Like?
This pyrazine explodes with an intensely green, sappy bell pepper aroma that’s almost shockingly realistic. The top note has a sharp vegetal punch reminiscent of freshly cut green peppers, with a subtle earthy undertone. As it evolves, the heart reveals a more refined green character – think dewy tomato leaves and young vine shoots. The dry-down is surprisingly clean, leaving just a whisper of peppery warmth. At high concentrations it can overwhelm, but when properly diluted, it adds remarkable freshness and verisimilitude to green fragrances.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to recreate the humid vegetal freshness after rainfall, combining with ginger and coriander for an edible green effect.
Provides the crisp green top note that complements the violet leaf, giving that famous ‘lawn clippings’ freshness.
2D Molecular Structure
SMILES: CCC(C)C1=NC=CN=C1OC
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Methoxy-3-(1-methylpropyl)pyrazine belongs to the alkylmethoxypyrazine class, powerful aroma compounds found naturally in bell peppers and some green vegetables. Synthetic production typically involves condensation reactions of appropriate diketones with hydrazine derivatives, followed by methylation. The branched isobutyl side chain contributes to its high odor potency and diffusion. Like most pyrazines, it’s stable across a wide pH range but can degrade under prolonged UV exposure.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Odor Threshold | Extremely low (ppb range) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.001-0.01% | Up to 0.05% | Extremely powerful – measure carefully |
| Functional Fragrance | 0.0005-0.005% | Up to 0.01% | Used in trace amounts for freshness |
Classic Accords
Tip: Always pre-dilute to 1% or lower before incorporating – undiluted material can dominate a formula.
Alternatives & Comparisons
More intense bell pepper character, used when maximum green impact is desired. Even more powerful – handle with care.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions currently apply to this material (as of Amendment 51).
GHS Classification
RIFM Assessment
RIFM has evaluated similar pyrazines but no specific assessment found for this isomer. Assume similar precautions apply.
Sustainability
As a synthetic material, this pyrazine has minimal environmental impact in production. It’s produced in closed systems with high atom economy. Its extreme potency means very small quantities are needed, reducing transportation impacts compared to natural alternatives like green pepper CO2 extracts.
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References
- Maga, J.A. (1982). Pyrazines in Foods: An Update. CRC Critical Reviews in Food Science and Nutrition. DOI:10.1080/10408398209527346
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID0047082
Physical Properties
| Molecular Weight | 166.224 g/mol🔬 EPA CompTox |
| Density | 0.99 g/cm^3🔬 EPA CTX |
| Boiling Point | 211.201 °C📊 OPERA |
| Melting Point | 58.73 °C📊 OPERA |
| Flash Point | 85.368 °C📊 OPERA |
| Refractive Index | 1.488 Dimensionless📊 OPERA |
| Molar Volume | 166.462 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.12 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.119 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.12 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.56 Log10 unitless📊 OPERA |
| Water Solubility | 0.032 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.049 mmHg📊 OPERA |
| Viscosity | 5.484 cP📊 OPERA |
| Surface Tension | 35.044 dyn/cm📊 OPERA |
| Thermal Conductivity | 131.011 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 35.01 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 3 count💻 Computed |
| Rotatable Bonds | 3 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 47.932 cm^3/mol📊 OPERA |
| Polarizability | 19.002 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.
