Methyl-beta-ionone (CAS 127-43-5) — Floral Heart to base Note Fragrance Ingredient
Methyl-beta-ionone
CAS 127-43-5
What Is Methyl-beta-ionone?
Methyl-beta-ionone is a synthetic fragrance ingredient commonly found in perfumes, soaps, and cosmetics. It contributes a violet-like floral scent with woody undertones. This versatile molecule helps create long-lasting floral accords in fine fragrances and personal care products.
Safety Profile
GENERALLY SAFEWhat Does Methyl-beta-ionone Smell Like?
Methyl-beta-ionone opens with a rich, powdery violet character reminiscent of Parma violets candies, quickly revealing a smooth orris-like earthiness. As it evolves, the scent develops woody facets resembling sandalwood, with a subtle fruity undertone recalling raspberry jam. The dry-down is remarkably persistent, leaving a delicate floral-woody trail that blends seamlessly with musks and amber materials. Its tenacity makes it invaluable for extending floral heart notes while adding sophistication to oriental and chypre compositions.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Provides the signature powdery iris-violet accord that defines this modern masculine, blending with cocoa and leather notes for a sophisticated gourmand effect.
Enhances the melancholic violet-iris theme, creating the impression of raindrops on flowers with its cool, powdery floralcy.
2D Molecular Structure
SMILES: CCC(=O)C=CC1=C(C)CCCC1(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
Methyl-beta-ionone belongs to the ionone class of compounds, characterized by a cyclohexenone ring structure. It’s produced through acid-catalyzed cyclization of pseudoionone, followed by selective methylation. The beta-position methylation increases stability and modifies the odor profile compared to alpha-ionone. Modern synthesis routes often employ zeolite catalysts for improved selectivity and yield. While not found in nature, it shares structural similarities with naturally occurring irones found in orris root.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | 266-268 °C |
| Density | 0.934 g/cm³ |
| Refractive Index | 1.497-1.502 |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-3% | Up to 5% | Floral-violet modifier |
| Soap | 0.5-1% | Up to 2% | Stable in alkaline conditions |
Classic Accords
Tip: Combine with ionone alpha at 3:1 ratio for a more natural violet effect.
Alternatives & Comparisons
More natural violet character but less stable. Use when a greener profile is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
IFRA Category 4 (leave-on): Max 2.1%. Category 5 (fine fragrance): Max 3.8%. Amendment 49.
EU Allergen Declaration
Not listed as EU allergen
GHS Classification
RIFM Assessment
RIFM assessment confirms safe use at current IFRA limits.
Sustainability
As a synthetic material, methyl-beta-ionone has consistent quality without natural sourcing constraints. Production typically uses petrochemical feedstocks, though some manufacturers are exploring bio-based precursors. Its high potency reduces environmental load per unit of fragrance.
Explore Methyl-beta-ionone
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References
- Bauer et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID6051643
Physical Properties
| Molecular Weight | 206.329 g/mol🔬 EPA CompTox |
| Density | 0.926 g/cm^3📊 OPERA |
| Boiling Point | 282.581 °C📊 OPERA |
| Melting Point | 46.762 °C📊 OPERA |
| Flash Point | 124.493 °C📊 OPERA |
| Refractive Index | 1.515 Dimensionless📊 OPERA |
| Molar Volume | 220.158 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 4.079 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 4.079 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 4.079 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 7.24 Log10 unitless📊 OPERA |
| Water Solubility | 0 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.027 mmHg📊 OPERA |
| Surface Tension | 32.971 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 | 66.337 cm^3/mol📊 OPERA |
| Polarizability | 26.298 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.
