Hexyl butyrate (CAS 2639-63-6) — Sweet Top Note Fragrance Ingredient
Hexyl butyrate
CAS 2639-63-6
What Is Hexyl butyrate?
Hexyl butyrate is a fruity-smelling compound commonly found in artificial fruit flavors and fragrances. You’ll encounter it in candies, beverages, and perfumes designed to mimic ripe tropical fruits. This ester matters because it provides an intense, natural-smelling fruitiness that’s more stable than actual fruit extracts. It helps create long-lasting fruity notes in everything from body sprays to gourmand perfumes.
Safety Profile
GENERALLY SAFEWhat Does Hexyl butyrate Smell Like?
Hexyl butyrate bursts with a juicy, tropical fruit explosion reminiscent of overripe pineapple and banana with hints of strawberry jam. The opening is intensely sweet and slightly fermented, like fruit liqueur. As it dries down, it develops a creamy, almost coconut-like undertone while maintaining its bright fruity character. The dry-down reveals a subtle green nuance that prevents it from becoming cloying, making it versatile for both fresh and gourmand compositions.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as the fruity backbone alongside raspberry and lychee to create the perfume’s hyper-realistic berry accord. Provides longevity to what would otherwise be fleeting top notes.
Forms the candied marshmallow-fruit effect when combined with vanilla and orange blossom. Responsible for the fragrance’s edible quality.
2D Molecular Structure
SMILES: CCCCCCOC(=O)CCC
Chemistry, Properties & Perfumer Guide
The Chemistry
Hexyl butyrate is a straight-chain ester formed by the condensation of hexanol and butyric acid. Industrially produced via acid-catalyzed esterification, it’s a workhorse molecule for fruity notes due to its stability and low production cost. The molecule lacks chirality, making synthesis straightforward without need for enantiomeric separation. Its relatively small size (MW 172.26) contributes to good volatility as a top note.
Physical & Chemical Properties
| Boiling Point | 208 °C |
|---|---|
| Density | 0.865 g/cm³ |
| Refractive Index | 1.416 |
| Flash Point | 82 °C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-3% | Up to 5% | Fruity top note |
| Functional Fragrance | 0.1-1% | Up to 2% | Candied fruit effects |
Classic Accords
Tip: Use with citrus oils to prevent the fruit note from becoming too heavy.
Alternatives & Comparisons
More volatile with sharper fruitiness. Better for fleeting top notes in citrus fragrances.
Greener, pear-like fruit character. Less sweet and jammy than hexyl butyrate.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No restrictions under IFRA standards.
RIFM Assessment
Evaluated by RIFM in 2003 with no safety concerns at current usage levels.
Sustainability
Synthesized from petrochemical feedstocks but requires minimal energy input due to simple production process. Not known to bioaccumulate. Biodegradation occurs via ester hydrolysis in wastewater systems.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press.
- RIFM (2003). Fragrance Ingredient Safety Assessment.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID8047559
Physical Properties
| Molecular Weight | 172.268 g/mol🔬 EPA CompTox |
| Density | 0.864 g/cm^3🔬 EPA CTX |
| Boiling Point | 206.8 °C🔬 EPA CTX |
| Melting Point | -78 °C🔬 EPA CTX |
| Flash Point | 81.175 °C🔬 EPA CTX |
| Refractive Index | 1.423 Dimensionless📊 OPERA |
| Molar Volume | 197.085 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.788 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.788 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.788 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.06 Log10 unitless📊 OPERA |
| Water Solubility | 0.001 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.319 mmHg🔬 EPA CTX |
| Viscosity | 1.406 cP📊 OPERA |
| Surface Tension | 27.681 dyn/cm📊 OPERA |
| Thermal Conductivity | 138.727 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 | 7 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 50.152 cm^3/mol📊 OPERA |
| Polarizability | 19.882 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.
