Cyclohexanone, 2-methyl-5-(1-methylethenyl)-, (2R,5R)- (CAS 5524-05-0) — Green Top to middle Note Fragrance Ingredient
Cyclohexanone, 2-methyl-5-(1-methylethenyl)-, (2R,5R)-
CAS 5524-05-0
What Is Cyclohexanone, 2-methyl-5-(1-methylethenyl)-, (2R,5R)-?
Cyclohexanone, 2-methyl-5-(1-methylethenyl)-, (2R,5R)- is a synthetic fragrance ingredient used in fine perfumery to add fresh, green, and slightly woody nuances. It’s commonly found in modern floral and fougère compositions. This molecule matters because its specific stereochemistry (2R,5R) creates unique odor properties that can’t be replicated by its stereoisomers, making it valuable for creating crisp, naturalistic green effects in fragrances.
Safety Profile
GENERALLY SAFEWhat Does Cyclohexanone, 2-methyl-5-(1-methylethenyl)-, (2R,5R)- Smell Like?
This stereospecific ketone delivers a vibrant green character reminiscent of freshly crushed leaves, with a clean citrus-herbal edge that evokes bergamot peel without the sweetness. The initial burst carries a slightly metallic sharpness that quickly mellows into a transparent woody-green base. Over time, it behaves like a chameleon – amplifying floral notes in the heart while maintaining an earthy dryness that prevents compositions from becoming cloying. Think of the difference between a generic ‘green’ candle versus standing in a damp forest after rain – this molecule captures that photorealistic quality.
2D Molecular Structure
SMILES: C[C@@H]1CC[C@H](CC1=O)C(C)=C
Chemistry, Properties & Perfumer Guide
The Chemistry
As a bicyclic monoterpenoid ketone, this molecule belongs to the same structural family as pulegone and menthone but with distinct stereochemical constraints. The (2R,5R) configuration creates a rigid molecular geometry that enhances volatility while limiting rotational freedom – key factors in its odor profile. Industrial synthesis typically involves acid-catalyzed cyclization of appropriate terpene precursors, with careful control needed to maintain stereochemical purity. The molecule’s compact structure gives it excellent stability in both acidic and basic conditions, making it formulation-friendly.
Physical & Chemical Properties
| Molecular Weight | 152.23 g/mol |
|---|---|
| Boiling Point | ~200°C (estimated) |
| XLogP | 2.5 (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-3% | Up to 5% | Green accent note |
| Functional Fragrances | 0.1-1% | Up to 2% | Freshness booster |
| Household Products | 0.05-0.5% | Up to 1% | Clean green nuance |
Classic Accords
Tip: Use with citrus top notes to prolong their freshness without sweetening.
Alternatives & Comparisons
When a more intense, galbanum-like green effect is desired without the subtle woody undertones.
For formulations requiring a softer, more floral-green character with better solubility in alcohol bases.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA. No specific use limitations.
RIFM Assessment
RIFM has not published a specific safety assessment for this stereoisomer.
Sustainability
As a purely synthetic material, this ingredient avoids agricultural supply chain issues but requires petrochemical feedstocks. The efficient synthesis route (typically 3-4 steps from common terpene precursors) gives it a relatively low carbon footprint compared to some natural isolates. Future biotech routes using engineered enzymes could make production more sustainable.
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References
- PubChem Compound Summary for CID 5524-05-0 PubChem
- Brenna, E. et al. (2003). Biocatalytic Methods for the Synthesis of Enantiopure Flavor Compounds. Chemical Reviews. DOI:10.1021/cr0106713
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 5524-05-0Physical Properties
| Molecular Weight | 152.23 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 2.7🔬 PubChem |
| Boiling Point | 220 °C🔬 EPA CompTox |
| Vapor Pressure | 0.2512 mmHg @ 25°C📊 OPERA |
| Flash Point | 81.1 °C🔬 EPA CompTox |
| Involatility Index | 0.0219💻 Calculated |
| log Kp (skin permeability) | -1.712💻 Calculated |
| SMILES | CC1CCC(CC1=O)C(=C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Slow💻 Calculated |
| Persistence Score | 1 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | warm• leffingwell |
| Functional Groups | ketonealkene💻 RDKit |
Sensory Thresholds
| Odor Detection Threshold | 0.82 ppm📖 van Gemert |
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: DTXSID80881218
Physical Properties
| Molecular Weight | 152.237 g/mol🔬 EPA CompTox |
| Density | 0.926 g/cm^3🔬 EPA CTX |
| Boiling Point | 217.168 °C📊 OPERA |
| Melting Point | 6.624 °C📊 OPERA |
| Flash Point | 79.399 °C📊 OPERA |
| Refractive Index | 1.457 Dimensionless📊 OPERA |
| Molar Volume | 168.475 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.85 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 2.645 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.645 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.98 Log10 unitless📊 OPERA |
| Water Solubility | 0.008 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.224 mmHg📊 OPERA |
| Viscosity | 2.031 cP📊 OPERA |
| Surface Tension | 29.566 dyn/cm📊 OPERA |
| Thermal Conductivity | 123.015 mW/(m*K)📊 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 | 1 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 45.886 cm^3/mol📊 OPERA |
| Polarizability | 18.19 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.
