alpha-Irone (CAS 79-69-6) — Floral Heart Note Fragrance Ingredient
alpha-Irone
CAS 79-69-6
What Is alpha-Irone?
Alpha-Irone is a synthetic fragrance molecule that mimics the violet-like scent found in orris root. You’ll encounter it in luxury perfumes, soaps, and cosmetics. This ingredient matters because it creates the powdery, floral-woody character prized in classic perfumery without requiring expensive natural orris extraction.
Safety Profile
GENERALLY SAFEWhat Does alpha-Irone Smell Like?
Alpha-Irone unfolds with an initial burst of violet petals dusted with powdered sugar, evolving into a velvety floral heart with subtle raspberry undertones. The dry-down reveals its woody foundation – like sandalwood shavings blended with dried iris rhizomes. It behaves like a chameleon, amplifying floral bouquets while adding a luxurious powderiness that lingers on skin for hours.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Alpha-Irone creates the signature orris-violet accord, blending with lily-of-the-valley for a contemporary interpretation of powdery florals.
Used alongside natural orris to extend the precious root’s powdery-woody character while maintaining brilliance in the floral heart.
Alpha-Irone provides the crisp, modern violet facet that contrasts with the earthy orris in this minimalist composition.
Amplifies the woody aspects of iris while maintaining the delicate floralcy, creating a seamless iris-wood fusion.
Alpha-Irone sharpens the metallic-cool facets of this radical iris interpretation without losing the powdery core.
2D Molecular Structure
SMILES: CC1CC=C(C)C(\C=C\C(C)=O)C1(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
Alpha-Irone belongs to the ionone class of ketones, structurally related to beta-ionone found in violets. The synthetic version typically exists as a racemic mixture, though the (6S)-alpha-isomer is most odor-active. Industrial synthesis often begins with citral or pseudoionone through cyclization and oxidation steps. Unlike natural orris which contains multiple irones, synthetic alpha-irone offers consistent quality and avoids the supply limitations of natural orris butter extraction.
Physical & Chemical Properties
| Boiling Point | ~250 °C (estimated) |
|---|---|
| Density | ~0.93 g/cm³ (estimated) |
| Refractive Index | ~1.495 (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Powdery floral modifier |
| Soap | 0.1-0.5% | Up to 1% | Stable in alkaline systems |
| Cosmetics | 0.05-0.3% | Up to 0.5% | Skin-safe at these levels |
| Candles | 0.3-1% | Up to 2% | Good heat stability |
Classic Accords
Tip: Combine with gamma-methyl ionone to create a more complex iris-violet illusion while reducing costs.
Alternatives & Comparisons
More woody and less powdery, suitable when wanting to reduce floralcy while maintaining iris character.
For structural support in woody bases, though lacks the distinctive powdery-violet facets.
Natural alternative with greater complexity but higher cost and variable quality.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions. Listed in IFRA Transparency List Amendment 49.
RIFM Assessment
RIFM safety assessment confirms safe use at current industry levels (2019 review).
Sustainability
Synthetic alpha-irone offers environmental advantages over natural orris, which requires 3-5 years of root aging and significant land use. Production from renewable citral sources is being developed. The consistent synthetic form reduces batch-to-batch variation and waste in fragrance compounding.
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References
- Bauer et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH. ISBN 978-3-527-30364-6
- Sell C. (2019). A Fragrant Introduction to Terpenoid Chemistry. RSC Publishing. DOI:10.1039/9781788016222
- IFRA Standards Library IFRA Amendment 49
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 79-69-6Physical Properties
| Molecular Weight | 206.32 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 3.2🔬 PubChem |
| Boiling Point | 110 °C🔬 EPA CompTox |
| log Kp (skin permeability) | -1.687💻 Calculated |
| SMILES | CC1CC=C(C(C1(C)C)C=CC(=O)C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
Odor & Flavor
| Primary Descriptors | floralsweet• leffingwell |
| Functional Groups | ketonealkene💻 RDKit |
| “The odor is soft, warm, Orris-Violet-like, sweet and extremely diffusive. Its true power and effect is clearly demonstrated in dilutions or in active use at concentrations near one percent in a perfume composition. The "lift" and the radiance introduced by this ketone are its greatest assets and advantages to compensate for its high cost.”📖 Arctander | |
| a- Irone has a rich, floral and natural character and constitutes an important element in orris and violet compositions as well as being useful when an exotic nuance is required. a-Irone is extremely diffusive, and it gives volume and tenacity to compositions. In combination with a-irisone (1:20, respectively) gives a natural orris effect.📖 Fenaroli | |
Flavor Notes (Arctander)
| “The taste is sweet, very powerful and, in proper dilution, fruity-berry-like.”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 0.002 ppm📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2597⚖️ FEMA GRAS |
| GRAS Status | Generally Recognized as Safe⚖️ FEMA GRAS |
| 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: DTXSID4047042
Physical Properties
| Molecular Weight | 206.329 g/mol🔬 EPA CompTox |
| Density | 0.907 g/cm^3📊 OPERA |
| Boiling Point | 271.327 °C📊 OPERA |
| Melting Point | 26.263 °C📊 OPERA |
| Flash Point | 111.911 °C📊 OPERA |
| Refractive Index | 1.5 Dimensionless📊 OPERA |
| Molar Volume | 225.65 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 4.256 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 4.256 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 4.256 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 6.67 Log10 unitless📊 OPERA |
| Water Solubility | 0.001 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.027 mmHg📊 OPERA |
| Surface Tension | 30.449 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 17.07 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 66.416 cm^3/mol📊 OPERA |
| Polarizability | 26.329 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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