Hexyl propionate (CAS 2445-76-3) — Sweet Top Note Fragrance Ingredient
Hexyl propionate
CAS 2445-76-3
What Is Hexyl propionate?
Hexyl propionate is a synthetic fragrance ingredient commonly found in fruity and floral perfumes, as well as some food flavorings. It contributes a fresh, sweet, and slightly green aroma reminiscent of ripe fruits. This ester is valued for its ability to add naturalistic fruity top notes that blend seamlessly with other fragrance components, making it a versatile building block in modern perfumery.
Safety Profile
GENERALLY SAFEWhat Does Hexyl propionate Smell Like?
Hexyl propionate bursts with a crisp, juicy fruitiness that suggests freshly cut pears and apples with a hint of banana. The initial impression is bright and slightly green, like the first bite of a just-ripened fruit. As it evolves, the sweetness becomes more rounded, taking on a faint floral undertone before settling into a clean, slightly waxy base reminiscent of fruit skins. The dry-down is subtle but persistent, leaving a trace of orchard-freshness that blends beautifully with floral and woody notes.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to enhance the crisp citrus top notes with a juicy fruit accent that bridges to the floral heart. Provides naturalistic freshness without overpowering the signature Sicilian lemon.
Adds a subtle fruity dimension to the classic citrus cologne structure. The ester’s volatility helps create the initial burst of freshness that defines this timeless composition.
2D Molecular Structure
SMILES: CCCCCCOC(=O)CC
Chemistry, Properties & Perfumer Guide
The Chemistry
Hexyl propionate is a simple ester formed from hexanol and propionic acid. As a synthetic material, it’s typically produced through acid-catalyzed esterification. The molecule lacks chiral centers, making stereochemistry irrelevant for its olfactory properties. Its relatively small size (molecular weight ~158 g/mol) contributes to its high volatility and top-note character in fragrance compositions.
Physical & Chemical Properties
| Boiling Point | ~180-185°C |
|---|---|
| Density | ~0.87 g/cm³ |
| Refractive Index | ~1.41 |
| Flash Point | ~70°C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-5% | Up to 10% | Fruity top note modifier |
| Functional Fragrance | 0.5-3% | Up to 5% | Freshness booster in soaps |
| Flavor | 10-50 ppm | Up to 100 ppm | Fruit flavor enhancer |
Classic Accords
Tip: Use in the first 5% of your formula to create immediate fruity impact that will evolve into floral notes.
Alternatives & Comparisons
More intensely fruity with stronger pear-like character. Use when needing brighter top notes with less sweetness.
Shorter chain version with more ethereal, rum-like quality. Better for creating lighter, more volatile effects.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions. Compliant under all categories in IFRA 51st Amendment.
RIFM Assessment
RIFM assessment confirms safe use at current industry levels with wide margin of safety.
Sustainability
As a synthetic material, hexyl propionate has consistent quality without natural variation. Production is energy-efficient with minimal waste streams. Not derived from petrochemical feedstocks but rather from renewable alcohol sources in modern manufacturing processes. Biodegradability is excellent due to simple ester structure.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781439812133
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 2445-76-3Physical Properties
| Molecular Weight | 158.24 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 2.9🔬 PubChem |
| Boiling Point | 73 °C🔬 EPA CompTox |
| Vapor Pressure | 1.4251 mmHg @ 25°C📊 OPERA |
| Flash Point | 72 °C🔬 EPA CompTox |
| Involatility Index | 0.1221💻 Calculated |
| log Kp (skin permeability) | -1.606💻 Calculated |
| SMILES | CCCCCCOC(=O)CC🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Moderate💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | earthyfruity• leffingwell |
| Functional Groups | esterether💻 RDKit |
| “Peculiar sweetish-sour, almost "earthy" odor, resembling the odor of overripe fruit on the ground, with sweet-earthy-herbaceous notes. Some observers have described the odor as resembling that of "a steaming tropical atmosphere".”📖 Arctander | |
| Hexyl propionate has an earthy, acrid odor suggestive of rotting fruits and a sweet, metallic-fruity taste.📖 Fenaroli | |
Flavor Notes (Arctander)
| “Sweet, metallic-rosy, almost "fermented" taste in dilutions lower than 50 ppm. This ester is used in flavor compositions mainly for imitation Cocoa or Chocolate and in a few types of fruit flavor.”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 0.008 ppm📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2576⚖️ FEMA GRAS |
| GRAS Status | Generally Recognized as Safe⚖️ FEMA GRAS |
| IOFI Classification | Nature Identical📖 Fenaroli |
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: DTXSID5047582
Physical Properties
| Molecular Weight | 158.241 g/mol🔬 EPA CompTox |
| Density | 0.869 g/cm^3🔬 EPA CTX |
| Boiling Point | 189.65 °C🔬 EPA CTX |
| Melting Point | -57.72 °C🔬 EPA CTX |
| Flash Point | 72 °C🔬 EPA CTX |
| Refractive Index | 1.418 Dimensionless📊 OPERA |
| Molar Volume | 180.578 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.23 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.23 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.23 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.45 Log10 unitless📊 OPERA |
| Water Solubility | 0.003 mol/L📊 OPERA |
| Henry's Law Constant | 0.001 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 1.125 mmHg🔬 EPA CTX |
| Viscosity | 1.221 cP📊 OPERA |
| Surface Tension | 26.959 dyn/cm📊 OPERA |
| Thermal Conductivity | 137.704 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 | 6 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 45.52 cm^3/mol📊 OPERA |
| Polarizability | 18.045 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.
