2-Isobutyl-3-methylpyrazine (CAS 13925-06-09) — Green Top to middle Note Fragrance Ingredient
2-Isobutyl-3-methylpyrazine
CAS 13925-06-09
What Is 2-Isobutyl-3-methylpyrazine?
2-Isobutyl-3-methylpyrazine is a synthetic aroma chemical used to create earthy, green, and bell pepper-like notes in perfumes and food flavorings. You’ll encounter it in fresh masculine fragrances and some gourmand scents. This pyrazine compound matters because it provides a naturalistic green vegetable effect at extremely low concentrations, allowing perfumers to add crisp, outdoor freshness without overpowering a composition.
Safety Profile
USE WITH AWARENESSWhat Does 2-Isobutyl-3-methylpyrazine Smell Like?
An explosion of freshly cut green bell peppers with an underlying damp earthiness dominates the initial impression of 2-Isobutyl-3-methylpyrazine. The sharp vegetal top evolves into a slightly sweet, nutty heart reminiscent of raw pea pods and freshly turned garden soil. In drydown, it leaves a delicate trace of warm hay and faintly mushroom-like earth tones. Exceptionally powerful – a drop can scent an entire room with its hyper-realistic green character that straddles the line between fresh produce and forest floor.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used at trace levels to enhance the fragrance’s signature verdant opening, contributing to its famous ‘just-cut lawn’ effect while blending seamlessly with violet leaf and iris.
This classic green floral employs the pyrazine to amplify its galbanum and hyacinth notes, creating an intense spring garden effect with remarkable longevity for a green note.
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Isobutyl-3-methylpyrazine belongs to the alkylpyrazine class, synthetic analogs of compounds found naturally in bell peppers, green peas, and roasted coffee. Manufactured through condensation reactions of amino acids or via Strecker degradation pathways, this asymmetric pyrazine contains a branched isobutyl group that enhances its volatility and green character. Unlike simpler pyrazines, the steric hindrance from its alkyl groups gives it exceptional odor potency at parts-per-billion levels while reducing harshness.
Physical & Chemical Properties
| Boiling Point | ~200 °C (estimated) |
|---|---|
| Vapor Pressure | 0.1 mmHg (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.01-0.05% | Up to 0.1% | Extremely potent – overdosing causes unpleasant mustiness |
| Functional Fragrance | 0.001-0.005% | Up to 0.01% | Used in air fresheners for ‘outdoor fresh’ effects |
Classic Accords
Tip: Always pre-dilute to 1% or lower before incorporating into blends to avoid overwhelming other materials.
Alternatives & Comparisons
The methoxy variant offers a slightly sweeter, less aggressive green character with better blending properties for floral compositions.
Simpler structure with sharper bell pepper notes but lacks the complexity and staying power of the methylated version.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA, but recommended usage below 0.1% in finished products due to potency.
EU Allergen Declaration
Not listed in EU allergen regulations.
GHS Classification
RIFM Assessment
RIFM has reviewed pyrazine safety data but no specific assessment available for this derivative.
Sustainability
As a synthetic material, 2-Isobutyl-3-methylpyrazine has minimal environmental impact in production compared to natural extracts requiring large-scale agriculture. Its extreme potency means very small quantities are needed, reducing resource consumption. Manufacturing typically uses petrochemical precursors, though some bio-based synthesis routes are being explored using fermentation-derived intermediates.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781439832275
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
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