5-Acetyl-3-isopropyl-1,1,2,6-tetramethylindane (CAS 68140-48-7) — Woody Base Note Fragrance Ingredient

Woody · Musky

5-Acetyl-3-isopropyl-1,1,2,6-tetramethylindane

CAS 68140-48-7

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

What Is 5-Acetyl-3-isopropyl-1,1,2,6-tetramethylindane?

5-Acetyl-3-isopropyl-1,1,2,6-tetramethylindane is a synthetic fragrance ingredient used in perfumery. It’s found in niche and designer fragrances, often contributing to woody or musky accords. This molecule matters because it helps create long-lasting, complex scent profiles while being more stable than some natural alternatives.

Safety Profile

GENERALLY SAFE
Generally safeUse with awarenessProfessional use
No major safety concerns reported
Limited toxicology data available
CAS
68140-48-7
Formula
Mixture
MW
Variable
Odor Family
Woody · Musky
Layer 1 · Enthusiast

What Does 5-Acetyl-3-isopropyl-1,1,2,6-tetramethylindane Smell Like?

This synthetic molecule delivers a sophisticated woody-musky character with subtle animalic undertones. The acetyl group introduces a dry, slightly powdery facet reminiscent of orris root, while the isopropyl and tetramethyl structure creates a smooth, ambery diffusion. It evolves from an initial crispness to a warm, skin-like base that lingers for hours. The dry-down reveals a clean muskiness comparable to well-aged cedarwood with a whisper of tobacco leaf.

Scent Profile
Layer 2

2D Molecular Structure

1-[2,3-Dihydro-1,1,2,6-tetramethyl-3-(1-methylethyl)-1H-inden-5-yl]ethanone

SMILES: CC(C)C1C(C)C(C)(C)C2=CC(C)=C(C=C12)C(C)=O

Chemistry, Properties & Perfumer Guide

The Chemistry

5-Acetyl-3-isopropyl-1,1,2,6-tetramethylindane belongs to the indane class of synthetic musks. Its structure combines acetyl and isopropyl substitutions on an indane core with four methyl groups creating steric hindrance. Synthesis typically involves Friedel-Crafts acylation of pre-formed tetramethylindane precursors. The molecule’s conformational rigidity contributes to its longevity in fragrance applications.

Physical & Chemical Properties

Perfumer Guide

Note Position
Base
Volatility
Very low (8+ hours)
Blending
Good
ApplicationTypical %RangeNotes
Fine Fragrance0.5-2%Up to 5%Base note fixative
Functional Fragrance0.1-1%Up to 3%Longevity enhancer

Classic Accords

Tip: Use as a bridge between woody and musky notes to enhance diffusion without overpowering.

Alternatives & Comparisons

1
Cashmeran CAS 33704-61-9

Similar woody-musky profile but with more pronounced cedar character and higher impact at lower concentrations.

2
Galaxolide CAS 1222-05-5

For cleaner musk effects when less woody character is desired.

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

Limited RIFM assessment available due to low production volume.

Sustainability

As a synthetic material, this ingredient avoids natural resource depletion concerns. Its production requires standard petrochemical inputs, with energy efficiency comparable to other fragrance synthetics. The molecule’s stability reduces environmental release compared to more volatile alternatives.

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References

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

    Report a data error

    Physicochemical Properties

    DTXSID: DTXSID9052393

    Physical Properties

    Molecular Weight 258.405 g/mol🔬 EPA CompTox
    Density 0.979 g/cm^3🔬 EPA CTX
    Boiling Point 321 °C🔬 EPA CTX
    Melting Point -50 °C🔬 EPA CTX
    Flash Point 127 °C🔬 EPA CTX
    Refractive Index 1.498 Dimensionless📊 OPERA
    Molar Volume 276.845 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 8.1 Log10 unitless🔬 EPA CTX
    LogD (pH 5.5) 5.539 Log10 unitless📊 OPERA
    LogD (pH 7.4) 5.539 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 7.88 Log10 unitless📊 OPERA
    Water Solubility 0 mol/L🔬 EPA CTX
    Henry's Law Constant 0 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 0.003 mmHg🔬 EPA CTX
    Surface Tension 29.442 dyn/cm📊 OPERA
    Thermal Conductivity 112.192 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 2 count💻 Computed
    Aromatic Rings 1 count💻 Computed
    Molar Refractivity 81.174 cm^3/mol📊 OPERA
    Polarizability 32.18 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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