Methyl-alpha-ionone (CAS 127-42-4) — Woody Heart to base Note Fragrance Ingredient
Methyl-alpha-ionone
CAS 127-42-4
What Is Methyl-alpha-ionone?
Methyl-alpha-ionone is a synthetic fragrance ingredient used in perfumes, body care, and household products. It’s known for its rich, woody-violet aroma that adds depth to floral and oriental compositions. This ingredient matters because it mimics natural violet notes at a fraction of the cost, while offering superior stability in formulations.
Safety Profile
GENERALLY SAFEWhat Does Methyl-alpha-ionone Smell Like?
Methyl-alpha-ionone opens with a bold violet-orris burst reminiscent of crushed flower petals, quickly evolving into a suede-like heart with hints of raspberry jam. The dry-down reveals its true character: a sophisticated woody-musk foundation with iris root nuances that lingers for hours. Like comparing a watercolor to oil paints, it’s more tenacious and radiant than natural ionones.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Provides the signature iris-violet accord that defines this modern masculine, blending with cocoa and leather notes for a sensual effect.
Used to reinforce the powdery violet theme, adding longevity to the classic floral-oriental structure.
2D Molecular Structure
SMILES: CCC(=O)\C=C\[C@H]1C(C)=CCCC1(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
Methyl-alpha-ionone is a synthetic terpenoid belonging to the ionone family. It’s produced through acid-catalyzed cyclization of pseudoionone, followed by methylation. The molecule features an extended conjugated system that modifies its odor profile compared to alpha-ionone, with greater diffusion and tenacity. Commercial products typically contain a mix of isomers.
Physical & Chemical Properties
| Boiling Point | 296 °C |
|---|---|
| Density | 0.93 g/cm³ |
| Flash Point | >100 °C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-5% | Up to 10% | Foundation for violet-iris accords |
| Soaps | 0.1-0.5% | Up to 1% | Provides stability in alkaline media |
Classic Accords
Tip: Use with ionones to create holographic violet effects.
Alternatives & Comparisons
More natural orris character but less tenacious
Softer, more powdery variation
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No restrictions under IFRA 49th Amendment.
EU Allergen Declaration
Not listed in EU allergen regulation.
RIFM Assessment
RIFM assessment concludes safe use at current levels.
Sustainability
Synthetic production avoids agricultural impacts of natural violet extracts. Modern manufacturing processes have reduced solvent waste and energy consumption compared to early 20th century methods.
Explore Methyl-alpha-ionone
Browse essential oils and aroma compounds.
Browse on iHerb →Affiliate disclosure: we may earn a small commission at no extra cost to you.
References
- Brenna et al. (2002). Biocatalytic preparation of natural flavours. Biotechnology Advances. DOI
- Sell (2006). The Chemistry of Fragrances. RSC Publishing. ISBN
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 127-42-4Physical Properties
| Molecular Weight | 206.32 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 3.4🔬 PubChem |
| Boiling Point | 271 °C🔬 EPA CompTox |
| Vapor Pressure | 0.0724 mmHg @ 25°C📊 OPERA |
| Flash Point | 122 °C🔬 EPA CompTox |
| Involatility Index | 0.0054💻 Calculated |
| log Kp (skin permeability) | -1.545💻 Calculated |
| SMILES | CCC(=O)C=CC1C(=CCCC1(C)C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 2.3 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | floralwoody• leffingwell |
| Functional Groups | ketonealkene💻 RDKit |
| “Occasionally CH3—CO-CH3 used as a diffusive topnote in perfumes, or as CaHeO = 58.08 an additive to colognes or other perfume solutions in order to make them smell more Colorless mobile liquid. odor of very poor tenacity.”📖 Arctander | |
| Methyl-a-ionone has an odor similar to a-ionone, but lighter and more rounded. It has a pleasant, fruity and sweet nuance.📖 Fenaroli | |
Regulatory Status
| IFRA Listed | Yes — see IFRA Standards for category limits⚖️ IFRA 51 |
| IOFI Classification | Artificial📖 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: DTXSID1051642
Physical Properties
| Molecular Weight | 206.329 g/mol🔬 EPA CompTox |
| Density | 0.919 g/cm^3📊 OPERA |
| Boiling Point | 274.172 °C📊 OPERA |
| Melting Point | 30.651 °C📊 OPERA |
| Flash Point | 119.273 °C📊 OPERA |
| Refractive Index | 1.509 Dimensionless📊 OPERA |
| Molar Volume | 222.165 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 4.257 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 4.257 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 4.257 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 6.91 Log10 unitless📊 OPERA |
| Water Solubility | 0.001 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.026 mmHg📊 OPERA |
| Surface Tension | 32.118 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 | 3 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 66.341 cm^3/mol📊 OPERA |
| Polarizability | 26.299 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.
Related Research
- L-Lactic acid (2-hydroxy propionic acid) (CAS 79-33-4) — Citrus Top to middle Note Fragrance Ingredient
- Citronellol (CAS 106-22-9) — Floral Heart Note Fragrance Ingredient
- 2-(p-Menth-1-ene-10-yl)cyclopentanone (CAS 95962-14-4) — Woody Top to Middle Note Fragrance Ingredient
- Patchouli Oil (CAS 8014-09-03) — Woody Base Note Fragrance Ingredient
