4,7-Methano-3aH-indene-3a-carboxylic acid, octahydro-, ethyl ester (CAS 129520-41-8) — Woody Base Note Fragrance Ingredient

Woody · Balsamic

4,_7-_Methano-_3aH-_indene-_3a-_carboxylic acid, octahydro-_, ethyl ester

CAS 129520-41-8

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

What Is 4,_7-_Methano-_3aH-_indene-_3a-_carboxylic acid, octahydro-_, ethyl ester?

This synthetic molecule is a specialized fragrance ingredient used in high-end perfumery. It is found in niche fragrances where unique woody-amber notes are desired. The ingredient matters because it offers perfumers a novel way to create depth and complexity without relying on traditional materials.

Safety Profile

USE WITH AWARENESS
Generally safeUse with awarenessProfessional use
Limited safety data available
Not currently restricted by IFRA
CAS
129520-41-8
Formula
Mixture
MW
Variable
Odor Family
Woody · Balsamic
Layer 1 · Enthusiast

What Does 4,_7-_Methano-_3aH-_indene-_3a-_carboxylic acid, octahydro-_, ethyl ester Smell Like?

A complex synthetic molecule with a nuanced olfactory profile. It opens with a sharp, almost metallic edge that quickly mellows into a warm, woody-amber heart. The dry-down reveals a subtle animalic undertone, reminiscent of aged leather or vintage musk. The evolution is slow and deliberate, making it ideal for long-lasting fragrances.

Scent Profile
Layer 2

2D Molecular Structure

4,7-Methano-3aH-indene-3a-carboxylic acid, octahydro-, ethyl ester

SMILES: [H]C12CCC([H])(C1)C1(CCCC21)C(=O)OCC

Chemistry, Properties & Perfumer Guide

The Chemistry

This ester is a synthetic molecule designed for its unique olfactory properties. It belongs to the class of bicyclic compounds, which often exhibit complex scent profiles. The molecule is typically synthesized through multi-step organic reactions, including esterification and hydrogenation. Its structure allows for excellent stability in various formulations.

Physical & Chemical Properties

Boiling PointN/A
DensityN/A

Perfumer Guide

Note Position
Base
Volatility
Low (hours to days)
Blending
Good
ApplicationTypical %RangeNotes
Fine Fragrance1-3%Up to 5%Used for depth and longevity

Classic Accords

Tip: Use sparingly to avoid overwhelming other notes.

Alternatives & Comparisons

1
Ambroxan CAS 6790-58-5

A more widely used amber note with better safety data.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

No current IFRA restrictions.

RIFM Assessment

No RIFM safety assessment available.

Sustainability

As a synthetic molecule, its environmental impact depends on production methods. Sustainable synthesis routes are being explored to minimize waste and energy use.

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References

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

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    Physicochemical Properties

    DTXSID: DTXSID70861029

    Physical Properties

    Molecular Weight 208.301 g/mol🔬 EPA CompTox
    Density 1.089 g/cm^3📊 OPERA
    Boiling Point 260.941 °C📊 OPERA
    Melting Point 72.611 °C📊 OPERA
    Flash Point 123.13 °C📊 OPERA
    Refractive Index 1.525 Dimensionless📊 OPERA
    Molar Volume 188.325 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 3.45 Log10 unitless📊 OPERA
    LogD (pH 5.5) 3.45 Log10 unitless📊 OPERA
    LogD (pH 7.4) 3.45 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 6.76 Log10 unitless📊 OPERA
    Water Solubility 0.001 mol/L📊 OPERA
    Henry's Law Constant 0 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 0.008 mmHg📊 OPERA
    Viscosity 7.652 cP📊 OPERA
    Surface Tension 41.469 dyn/cm📊 OPERA
    Thermal Conductivity 119.248 mW/(m*K)📊 OPERA

    Molecular Descriptors

    Topological Polar Surface Area 26.3 Ų💻 Computed
    H-Bond Donors 0 count💻 Computed
    H-Bond Acceptors 2 count💻 Computed
    Rotatable Bonds 2 count💻 Computed
    Aromatic Rings 0 count💻 Computed
    Molar Refractivity 57.706 cm^3/mol📊 OPERA
    Polarizability 22.877 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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