4,4a,6,7,8,8a-Hexahydro-1,4-methanonaphthalen-5(1H)-one (CAS 51519-65-4) — Woody Middle to base Note Fragrance Ingredient
4,4a,6,7,8,8a-Hexahydro-1,4-methanonaphthalen-5(1H)-one
CAS 51519-65-4
What Is 4,4a,6,7,8,8a-Hexahydro-1,4-methanonaphthalen-5(1H)-one?
This synthetic fragrance ingredient is a complex bicyclic ketone used in modern perfumery to create woody-ambery accords. It’s found in niche and designer fragrances seeking a sophisticated, slightly camphoraceous character. The molecule offers perfumers a unique bridge between dry woods and warm ambers, contributing to contemporary scent profiles that balance freshness with depth.
Safety Profile
USE WITH AWARENESSWhat Does 4,4a,6,7,8,8a-Hexahydro-1,4-methanonaphthalen-5(1H)-one Smell Like?
A sophisticated woody-ambery character unfolds with an initial crisp, camphor-like freshness reminiscent of crushed pine needles. The heart reveals a smooth transition into warm, slightly musky undertones with facets of aged cedarwood and distant leather. Dry-down presents a subtle powdery-amber quality that lingers close to the skin, creating an elegant trail. The overall impression is of a modern interpretation of classic woody materials, offering both diffusion and tenacity.
2D Molecular Structure
SMILES: O=C1CCCC2C3CC(C=C3)C12
Chemistry, Properties & Perfumer Guide
The Chemistry
This bicyclic ketone belongs to the family of norcamphor derivatives, synthesized through Diels-Alder reactions of cyclopentadiene with appropriate dienophiles followed by oxidation. The rigid molecular framework creates distinctive odor characteristics through its constrained conformational geometry. While purely synthetic in commercial use, related structures occur naturally in some resinous materials. The molecule’s compact size contributes to good volatility and diffusion properties.
Physical & Chemical Properties
| Molecular Class | Bicyclic ketone |
|---|---|
| Structural Type | Norcamphor derivative |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-3% | Up to 5% | Woody-amber modifier |
| Functional Fragrance | 0.5-1% | Up to 2% | Dry woody accent |
Classic Accords
Tip: Use as a bridge between fresh top notes and deep base materials to enhance diffusion.
Alternatives & Comparisons
Offers similar woody-diffusive properties with greater tenacity and less camphoraceous character.
Provides comparable woody aspects with smoother amber undertones and better blending versatility.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No specific restrictions under current IFRA standards (Amendment 49).
RIFM Assessment
Not currently evaluated by RIFM – considered safe at standard usage levels based on structural analogs.
Sustainability
As a synthetic material, this compound avoids natural resource depletion concerns. Production typically involves petrochemical feedstocks, though modern synthesis routes aim for atom efficiency. The material’s potency allows for low usage levels, reducing environmental load compared to less powerful alternatives.
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Physicochemical Properties
DTXSID: DTXSID2052154
Physical Properties
| Molecular Weight | 162.232 g/mol🔬 EPA CompTox |
| Density | 1.088 g/cm^3📊 OPERA |
| Boiling Point | 255.557 °C📊 OPERA |
| Melting Point | 16.218 °C📊 OPERA |
| Flash Point | 100.234 °C📊 OPERA |
| Refractive Index | 1.546 Dimensionless📊 OPERA |
| Molar Volume | 146.977 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.148 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.148 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.148 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.73 Log10 unitless📊 OPERA |
| Water Solubility | 0.004 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.024 mmHg📊 OPERA |
| Viscosity | 6.978 cP📊 OPERA |
| Surface Tension | 37.122 dyn/cm📊 OPERA |
| Thermal Conductivity | 118.64 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 | 0 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 46.568 cm^3/mol📊 OPERA |
| Polarizability | 18.461 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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