2,2,4,6,6-Pentamethylheptane (CAS 13475-82-6) — Woody Base Note Fragrance Ingredient
2,2,4,6,6-Pentamethylheptane
CAS 13475-82-6
What Is 2,2,4,6,6-Pentamethylheptane?
2,2,4,6,6-Pentamethylheptane is a synthetic hydrocarbon used as a fragrance ingredient. It’s found in some modern perfumes as a subtle woody-musky base note. This ingredient matters because it provides stability and longevity to fragrances, helping other scent components last longer on the skin without overpowering them.
Safety Profile
GENERALLY SAFEWhat Does 2,2,4,6,6-Pentamethylheptane Smell Like?
A clean, dry hydrocarbon with faint woody undertones reminiscent of freshly planed cedar. Its odor is deliberately subtle – acting more as a fixative than a distinct scent. The molecule provides a smooth, slightly powdery dry-down that helps blend sharper top notes into a fragrance’s heart. Under laboratory conditions, it presents as nearly odorless at low concentrations, developing a barely perceptible pencil shavings character when undiluted.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as the sole active ingredient in this minimalist fragrance, showcasing how synthetic hydrocarbons can create subtle yet persistent skin scents.
Employed as an invisible fixative to extend the coastal woody accord without adding noticeable weight.
2D Molecular Structure
SMILES: CC(CC(C)(C)C)CC(C)(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
2,2,4,6,6-Pentamethylheptane belongs to the branched alkane family, synthesized through oligomerization of isobutene. Its highly branched structure gives it exceptional stability and low reactivity. The multiple methyl groups create steric hindrance that prevents rapid oxidation, contributing to its longevity in fragrance formulations. Unlike many fragrance ingredients, it lacks functional groups entirely, making it chemically inert and resistant to degradation.
Physical & Chemical Properties
| Appearance | Colorless liquid |
|---|---|
| Molecular Weight | 170.33 g/mol |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-3% | Up to 5% | Used as fixative rather than primary scent |
| Functional Fragrance | 0.5-2% | Up to 3% | Adds longevity to air fresheners |
Classic Accords
Tip: Use to extend citrus top notes in eau de colognes without muddying freshness.
Alternatives & Comparisons
Offers similar fixative properties with more pronounced woody character when higher odor impact is desired.
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 due to low usage volume and minimal exposure concerns.
Sustainability
As a petrochemical derivative, its production carries typical hydrocarbon processing environmental impacts. However, its extreme potency at low concentrations makes it relatively sustainable per unit of fragrance performance. Not known to bioaccumulate due to molecular structure.
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References
- Branched Alkanes in Modern Perfumery Industry publication
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 13475-82-6Physical Properties
| Molecular Weight | 170.33 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 5.6🔬 PubChem |
| Boiling Point | 177.8 °C🔬 EPA CompTox |
| Vapor Pressure | 11.2202 mmHg @ 25°C📊 OPERA |
| Flash Point | 45 °C🔬 EPA CompTox |
| Involatility Index | 0.9266💻 Calculated |
| log Kp (skin permeability) | 0.237💻 Calculated |
| SMILES | CC(CC(C)(C)C)CC(C)(C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Moderate💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | muskywoody• leffingwell |
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: DTXSID0042034
Physical Properties
| Molecular Weight | 170.34 g/mol🔬 EPA CompTox |
| Density | 0.74 g/cm^3🔬 EPA CTX |
| Boiling Point | 177.8 °C🔬 EPA CTX |
| Melting Point | -69.8 °C🔬 EPA CTX |
| Flash Point | 53.983 °C🔬 EPA CTX |
| Refractive Index | 1.421 Dimensionless📊 OPERA |
| Molar Volume | 227.09 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 5.403 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 5.403 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 5.403 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.32 Log10 unitless📊 OPERA |
| Water Solubility | 0 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0.155 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 5.212 mmHg📊 OPERA |
| Viscosity | 0.803 cP📊 OPERA |
| Surface Tension | 21.577 dyn/cm📊 OPERA |
| Thermal Conductivity | 100.436 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 0 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 0 count💻 Computed |
| Rotatable Bonds | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 57.533 cm^3/mol📊 OPERA |
| Polarizability | 22.808 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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