2-Isobutyl-3-methoxypyrazine (CAS 24683-00-9) — Green Top to heart Note Fragrance Ingredient
2-Isobutyl-3-methoxypyrazine
CAS 24683-00-9
What Is 2-Isobutyl-3-methoxypyrazine?
2-Isobutyl-3-methoxypyrazine is a powerful synthetic aroma chemical that gives a distinct green bell pepper or galbanum-like scent. You’ll encounter it in minute quantities in perfumes and some food flavorings. This molecule matters because it’s one of the most potent odorants known – a single drop can scent an entire room, making it invaluable for creating realistic green notes in fragrances.
Safety Profile
USE WITH AWARENESSWhat Does 2-Isobutyl-3-methoxypyrazine Smell Like?
A razor-sharp green explosion reminiscent of freshly cut bell peppers with an underlying earthy complexity. The initial burst is intensely vegetal – like crushing green stems between your fingers – which gradually softens into a dry, slightly nutty character. At ultra-low concentrations, it adds remarkable freshness and verisimilitude to green accords. The dry-down reveals a subtle mushroom-like earthiness that makes it particularly useful for creating lifelike garden effects.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
The reformulated version uses 2-isobutyl-3-methoxypyrazine to recreate the legendary green burst of the original, contributing an ultra-realistic crushed leaf effect that defines the fragrance’s spring-like character.
Jean-Claude Ellena employs this pyrazine to craft the photorealistic green mango note, where its sharp greenness contrasts beautifully with the fruity sweetness.
2D Molecular Structure
SMILES: COC1=NC=CN=C1CC(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Isobutyl-3-methoxypyrazine belongs to the alkylmethoxypyrazine class, which includes some of nature’s most potent odorants. While found naturally in bell peppers and galbanum, the synthetic version is preferred for consistency. It’s typically synthesized through condensation reactions of aminoacetone derivatives with isobutyraldehyde, followed by methylation. The molecule’s extreme potency stems from its low odor threshold (around 0.002 parts per trillion in air) and specific binding to olfactory receptors.
Physical & Chemical Properties
| Odor Threshold | 0.002 ppt in air |
|---|---|
| Potency | 1 million times more potent than vanillin |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.001-0.01% | Up to 0.05% | Extremely powerful – use in dilution |
| Functional Fragrance | 0.0001-0.001% | Up to 0.005% | For green household product scents |
Classic Accords
Tip: Always pre-dilute to 0.1% or lower before incorporating into blends to avoid overwhelming other materials.
Alternatives & Comparisons
Similar green character but with earthier, more potato-like nuances. Slightly less intense, useful when a softer green 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 but subject to general pyrazine guidelines.
RIFM Assessment
RIFM has evaluated similar pyrazines but no specific assessment found for this compound.
Sustainability
As a synthetic material, 2-isobutyl-3-methoxypyrazine has minimal environmental impact in production. Its extreme potency means very small quantities are needed, reducing overall chemical usage. Some perfumers prefer it over natural galbanum extracts which can have sustainability concerns regarding wild harvesting.
Explore 2-Isobutyl-3-methoxypyrazine
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References
- Maga (1982). Pyrazines in Foods. CRC Critical Reviews in Food Science and Nutrition.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 24683-00-9Physical Properties
| Molecular Weight | 166.22 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 2.6🔬 PubChem |
| Boiling Point | 187 °C🔬 EPA CompTox |
| Vapor Pressure | 0.0339 mmHg @ 25°C📊 OPERA |
| Flash Point | 80 °C🔬 EPA CompTox |
| Involatility Index | 0.0028💻 Calculated |
| log Kp (skin permeability) | -1.868💻 Calculated |
| SMILES | CC(C)CC1=NC=CN=C1OC🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 2.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | green• leffingwell |
| Functional Groups | etheraromatic💻 RDKit |
| 2-Isobutyl-3-methoxypyrazine has an extremely powerful odor. Diluted water solutions of this compound exhibit a characteristic odor of green bell peppers.📖 Fenaroli | |
Sensory Thresholds
| Odor Detection Threshold | 0 ppm (n=14)📖 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: DTXSID9051907
Physical Properties
| Molecular Weight | 166.224 g/mol🔬 EPA CompTox |
| Density | 0.993 g/cm^3🔬 EPA CTX |
| Boiling Point | 205.229 °C📊 OPERA |
| Melting Point | 45.635 °C📊 OPERA |
| Flash Point | 86.38 °C📊 OPERA |
| Refractive Index | 1.488 Dimensionless📊 OPERA |
| Molar Volume | 166.091 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.085 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.084 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.085 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.56 Log10 unitless📊 OPERA |
| Water Solubility | 0.031 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 0.109 mmHg📊 OPERA |
| Viscosity | 4.05 cP📊 OPERA |
| Surface Tension | 34.397 dyn/cm📊 OPERA |
| Thermal Conductivity | 130.57 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 | 47.888 cm^3/mol📊 OPERA |
| Polarizability | 18.984 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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