Heneicosane (CAS 629-94-7) — Woody Base Note Fragrance Ingredient
Heneicosane
CAS 629-94-7
What Is Heneicosane?
Heneicosane is a synthetic hydrocarbon used in specialty fragrance applications. It’s primarily encountered in laboratory settings rather than consumer products. This long-chain alkane serves as a subtle fixative in some perfumes, helping to extend the life of more volatile fragrance components without adding its own strong scent.
Safety Profile
GENERALLY SAFEWhat Does Heneicosane Smell Like?
Heneicosane is nearly odorless to most people, though some may detect a faint waxy, paraffin-like character at high concentrations. As a straight-chain alkane, it lacks the functional groups that typically produce distinctive aromas. Its primary value in perfumery comes from its physical properties rather than olfactive contribution, serving as an invisible backbone that subtly modifies the evaporation profile of fragrance compositions.
2D Molecular Structure
SMILES: CCCCCCCCCCCCCCCCCCCCC
Chemistry, Properties & Perfumer Guide
The Chemistry
Heneicosane is a straight-chain hydrocarbon with 21 carbon atoms (C21H44), classified as an alkane. It’s synthetically produced through petroleum refining or Fischer-Tropsch processes. Unlike many fragrance ingredients, heneicosane lacks functional groups, making it chemically inert and odor-neutral. Its long carbon chain gives it high molecular weight and low volatility, which explains its use as a fixative in fragrance applications.
Physical & Chemical Properties
| Melting Point | 40-42 °C |
|---|---|
| Boiling Point | 356-357 °C |
| Appearance | White crystalline solid |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Fixative base note |
| Functional Products | 1-3% | Up to 8% | Evaporation rate modifier |
Classic Accords
Tip: Use as an invisible fixative in heavy oriental bases where traditional materials might interfere with the scent profile.
Alternatives & Comparisons
Similar hydrocarbon fixative with slightly higher molecular weight for even lower volatility.
Shorter chain hydrocarbon that provides similar functionality with slightly more mobility in blends.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted by IFRA. No usage limits apply.
RIFM Assessment
RIFM has evaluated similar long-chain alkanes as safe for current fragrance use levels.
Sustainability
As a petroleum-derived synthetic, heneicosane raises typical petrochemical sustainability concerns. However, its extreme potency at low usage levels minimizes environmental impact per finished product. Some manufacturers are exploring bio-based production routes from renewable feedstocks.
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References
- PubChem Compound Summary for Heneicosane PubChem CID:12391
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPerfumer’s Notes
Odor: alkane
MW: 296.6
LogP: 11
Ingredient Data Sheet
CAS 629-94-7Physical Properties
| Molecular Weight | 296.6 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 11🔬 PubChem |
| Boiling Point | 356.5 °C🔬 EPA CompTox |
| Vapor Pressure | 8.73 mmHg @ 25°C📊 OPERA |
| Flash Point | 45 °C🔬 EPA CompTox |
| Involatility Index | 0.5463💻 Calculated |
| log Kp (skin permeability) | 3.301💻 Calculated |
| SMILES | CCCCCCCCCCCCCCCCCCCCC🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Moderate💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
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: DTXSID9047097
Physical Properties
| Molecular Weight | 296.583 g/mol🔬 EPA CompTox |
| Density | 0.792 g/cm^3🔬 EPA CTX |
| Boiling Point | 357.15 °C🔬 EPA CTX |
| Melting Point | 40.353 °C🔬 EPA CTX |
| Flash Point | 129.025 °C🔬 EPA CTX |
| Refractive Index | 1.442 Dimensionless📊 OPERA |
| Molar Volume | 375.177 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 10.312 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 10.312 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 10.312 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 9.38 Log10 unitless📊 OPERA |
| Water Solubility | 0 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0 mmHg🔬 EPA CTX |
| Viscosity | 4.979 cP📊 OPERA |
| Surface Tension | 27.793 dyn/cm📊 OPERA |
| Thermal Conductivity | 145.659 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 | 18 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 99.339 cm^3/mol📊 OPERA |
| Polarizability | 39.381 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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