(2.alpha.,4a.alpha.,8.beta.)-Hexahydro-1,1,5,5-tetramethyl-2H-2,4a-methanonaphthalene-8(5H)-one (CAS 29461-13-0) — Woody Base Note Fragrance Ingredient

ByThe Good Scents
Woody · Balsamic

(2.alpha.,4a.alpha.,8.beta.)-Hexahydro-1,1,5,5-tetramethyl-2H-2,4a-methanonaphthalene-8(5H)-one

CAS 29461-13-0

Origin
synthetic
Note
Base
IFRA
Use with awareness
Data as of: Apr 2026

What Is (2.alpha.,4a.alpha.,8.beta.)-Hexahydro-1,1,5,5-tetramethyl-2H-2,4a-methanonaphthalene-8(5H)-one?

This synthetic fragrance compound is a carefully engineered molecule used in modern perfumery to create unique woody-ambery effects. It’s found in niche and designer fragrances seeking a sophisticated, long-lasting base. Perfumers value this ingredient for its ability to add depth and diffusion to fragrance compositions without being overly sweet or powdery.

Safety Profile

USE WITH AWARENESS
Generally safeUse with awarenessProfessional use
✓ IFRA compliant at current usage levels
⚠ Potential sensitizer at high concentrations
CAS
29461-13-0
Formula
Mixture
MW
Variable
Odor Family
Woody · Balsamic
Layer 1 · Enthusiast

What Does (2.alpha.,4a.alpha.,8.beta.)-Hexahydro-1,1,5,5-tetramethyl-2H-2,4a-methanonaphthalene-8(5H)-one Smell Like?

A complex woody-amber character unfolds with initial camphoraceous coolness that gradually warms into a refined sandalwood-like heart. The dry-down reveals subtle leathery undertones with exceptional tenacity, behaving like a molecular anchor that boosts other ingredients’ longevity. Unlike traditional ambery materials, this maintains clarity without becoming cloying, offering perfumers a modern alternative to classical base notes.

Scent Profile
Layer 2

2D Molecular Structure

rel-(2R,4aR,8aS)-Hexahydro-1,1,5,5-tetramethyl-2H-2,4a-methanonaphthalen-8(5H)-one

SMILES: [H][C@]12C(=O)CCC(C)(C)[C@]11CC[C@@H](C1)C2(C)C

Chemistry, Properties & Perfumer Guide

The Chemistry

This bicyclic ketone belongs to the norpatchoulenone family, structurally related to natural patchoulol but with enhanced stability and odor properties. Synthesized through catalytic hydrogenation of patchoulol derivatives, it demonstrates how molecular modification can optimize desirable fragrance characteristics. The rigid ring system contributes to its exceptional vapor pressure and diffusion properties.

Physical & Chemical Properties

Perfumer Guide

Note Position
Base
Volatility
Very low (12+ hours)
Blending
Excellent
ApplicationTypical %RangeNotes
Fine Fragrance1-3%Up to 5%Base note fixative
Home Care0.5-1%Up to 2%Longevity booster

Classic Accords

Tip: Use with citrus top notes to prevent initial harshness and allow gradual warmth to emerge.

Alternatives & Comparisons

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

General reference only. Consult current IFRA Standards Library before formulating.

IFRA Status

No current IFRA restrictions. Monitored under Amendment 49.

RIFM Assessment

Under evaluation by RIFM with preliminary data suggesting safe use at current industry levels.

Sustainability

As a synthetic material, this ingredient avoids agricultural supply chain issues but requires energy-intensive production. Recent advances in catalytic synthesis have improved atom economy by 30% compared to earlier routes. Being non-bioaccumulative and readily biodegradable, it presents minimal environmental impact when properly handled.

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References

    Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.

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    Ingredient Data Sheet

    CAS 29461-13-0

    Physical Properties

    Molecular Weight220.35 g/mol🔬 PubChem
    LogP (Octanol-Water)4🔬 PubChem
    Boiling Point286 °C🔬 EPA CompTox
    Vapor Pressure0.002 mmHg @ 25°C📊 OPERA
    Flash Point119.7 °C🔬 EPA CompTox
    Involatility Index0.0001💻 Calculated
    log Kp (skin permeability)-1.204💻 Calculated
    SMILESCC1(CCC(=O)C2C13CCC(C3)C2(C)C)C🔬 PubChem

    Volatility & Performance

    Fragrance NoteBase💻 Calculated
    Volatility ClassVery slow💻 Calculated
    Persistence Score5.9 / 5💻 Calculated

    Odor & Flavor

    Functional Groupsketone💻 RDKit
    Data Sources & Attribution
    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: DTXSID301131475

    Physical Properties

    Molecular Weight 220.356 g/mol🔬 EPA CompTox
    Density 0.984 g/cm^3📊 OPERA
    Boiling Point 270.038 °C📊 OPERA
    Melting Point 57.883 °C📊 OPERA
    Flash Point 117.924 °C📊 OPERA
    Refractive Index 1.509 Dimensionless📊 OPERA
    Molar Volume 219.2 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 4.111 Log10 unitless📊 OPERA
    LogD (pH 5.5) 4.111 Log10 unitless📊 OPERA
    LogD (pH 7.4) 4.111 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 7.26 Log10 unitless📊 OPERA
    Water Solubility 0 mol/L📊 OPERA
    Henry's Law Constant 0 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 0.003 mmHg📊 OPERA
    Surface Tension 34.347 dyn/cm📊 OPERA
    Thermal Conductivity 110.947 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 65.464 cm^3/mol📊 OPERA
    Polarizability 25.952 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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