Spiro[5.5]undec-8-en-1-one, 2,2,7,9-tetramethyl- (CAS 502847-01-0) — Musky Base Note Fragrance Ingredient

ByThe Good Scents
Musky · Woody

Spiro[5.5]undec-8-en-1-one, 2,2,7,9-tetramethyl-

CAS 502847-01-0

Origin
synthetic
Note
Base
IFRA
Generally safe
Data as of: Apr 2026

What Is Spiro[5.5]undec-8-en-1-one, 2,2,7,9-tetramethyl-?

This synthetic fragrance ingredient is a specialized musk compound used in modern perfumery. It’s found in premium personal care products and niche fragrances. The molecule’s unique structure provides long-lasting olfactory effects while meeting contemporary safety standards for musk alternatives.

Safety Profile

GENERALLY SAFE
Generally safeUse with awarenessProfessional use
✓ Not restricted by IFRA
✓ No known allergen status
CAS
502847-01-0
Formula
Mixture
MW
Variable
Odor Family
Musky · Woody
Layer 1 · Enthusiast

What Does Spiro[5.5]undec-8-en-1-one, 2,2,7,9-tetramethyl- Smell Like?

This synthetic musk presents a clean, modern olfactory profile with exceptional tenacity. The initial impression is a crisp, slightly metallic muskiness that evolves into a velvety-smooth skin-like warmth. Unlike traditional musks, it carries subtle woody-amber undertones without animalic heaviness. The dry-down reveals remarkable persistence, leaving a sophisticated trail that blends seamlessly with floral and woody accords.

Scent Profile
Layer 2

2D Molecular Structure

Spiro[5.5]undec-8-en-1-one, 2,2,7,9-tetramethyl-

SMILES: CC1C=C(C)CCC11CCCC(C)(C)C1=O

Chemistry, Properties & Perfumer Guide

The Chemistry

This spirocyclic ketone belongs to the class of synthetic macrocyclic musks, designed to mimic natural musk compounds while avoiding environmental persistence issues. The molecule’s rigid spiro structure contributes to its exceptional stability and diffusion properties. Synthesis typically involves Diels-Alder reactions followed by selective oxidation steps to create the characteristic ketone functionality.

Physical & Chemical Properties

Perfumer Guide

Note Position
Base
Volatility
Very low (12+ hours)
Blending
Excellent
ApplicationTypical %RangeNotes
Fine Fragrance0.5-2%Up to 5%Modern musk foundation
Body Care0.1-0.5%Up to 1%Long-lasting skin effect

Classic Accords

Tip: Use as a musk enhancer in woody-floral compositions where traditional musks would be too heavy.

Alternatives & Comparisons

1
Ethylene Brassylate CAS 105-95-3

A more affordable macrocyclic musk with similar tenacity but less woody character.

2
Muscenone CAS 110037-71-1

Higher-end musk alternative with more pronounced animalic facets.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

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

IFRA Status

Not currently restricted by IFRA standards.

RIFM Assessment

No specific RIFM assessment found for this compound.

Sustainability

As a synthetic musk, this compound was developed specifically to address environmental concerns associated with traditional musks. It demonstrates good biodegradability while providing excellent performance. The manufacturing process follows green chemistry principles with minimal waste generation.

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References

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

    Report a data error

    Ingredient Data Sheet

    CAS 502847-01-0

    Physical Properties

    Molecular Weight220.35 g/mol🔬 PubChem
    LogP (Octanol-Water)3.5🔬 PubChem
    Boiling Point295 °C🔬 EPA CompTox
    Vapor Pressure0.0098 mmHg @ 25°C📊 OPERA
    Flash Point141.9 °C🔬 EPA CompTox
    Involatility Index0.0007💻 Calculated
    log Kp (skin permeability)-1.559💻 Calculated
    SMILESCC1C=C(CCC12CCCC(C2=O)(C)C)C🔬 PubChem

    Volatility & Performance

    Fragrance NoteBase💻 Calculated
    Volatility ClassVery slow💻 Calculated
    Persistence Score4.1 / 5💻 Calculated

    Odor & Flavor

    Functional Groupsketonealkene💻 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: DTXSID00889190

    Physical Properties

    Molecular Weight 220.356 g/mol🔬 EPA CompTox
    Density 0.947 g/cm^3📊 OPERA
    Boiling Point 289.292 °C📊 OPERA
    Melting Point 40.401 °C📊 OPERA
    Flash Point 134.092 °C📊 OPERA
    Refractive Index 1.496 Dimensionless📊 OPERA
    Molar Volume 230.153 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 4.468 Log10 unitless📊 OPERA
    LogD (pH 5.5) 4.468 Log10 unitless📊 OPERA
    LogD (pH 7.4) 4.468 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 7.55 Log10 unitless📊 OPERA
    Water Solubility 0.001 mol/L📊 OPERA
    Henry's Law Constant 0 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 0.004 mmHg📊 OPERA
    Viscosity 3.43 cP📊 OPERA
    Surface Tension 32.712 dyn/cm📊 OPERA
    Thermal Conductivity 118.714 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 67.202 cm^3/mol📊 OPERA
    Polarizability 26.641 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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