Isoamyl butyrate (CAS 106-27-4) — Sweet Top Note Fragrance Ingredient
Isoamyl butyrate
CAS 106-27-4
What Is Isoamyl butyrate?
Isoamyl butyrate is a fruity ester commonly used to create banana and pear notes in food flavorings and some fragrances. You’ll encounter it in candy, gum, and occasionally in tropical or dessert-inspired perfumes. This molecule matters because it delivers an intense, realistic fruitiness at very low concentrations, allowing perfumers to create juicy, mouthwatering effects without overwhelming a composition.
Safety Profile
GENERALLY SAFEWhat Does Isoamyl butyrate Smell Like?
Isoamyl butyrate bursts with hyper-realistic banana runt candy – that intense, almost artificial sweetness that somehow smells delicious. Within minutes, it softens into a more natural pear-like juiciness with a subtle boozy undertone. The dry-down reveals a faint buttery creaminess, like the memory of banana cream pie lingering on skin. While potent, it behaves well in blends, adding a candied fruit lift that never turns syrupy or cloying when properly dosed.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the tropical fruit accord, isoamyl butyrate provides the signature banana-like sweetness that makes this fragrance instantly recognizable. It blends seamlessly with mango and passionfruit notes.
The banana note in this gourmand owes its realism to isoamyl butyrate, which creates a dessert-like effect when paired with vanilla and caramel accords without turning artificial.
2D Molecular Structure
SMILES: CCCC(=O)OCCC(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
Isoamyl butyrate is an ester formed from the reaction of isopentanol (isoamyl alcohol) and butyric acid. This simple ester is almost exclusively produced synthetically for perfumery, though trace amounts occur naturally in bananas and some other fruits. Industrial synthesis typically uses acid-catalyzed esterification under reflux. The molecule lacks chirality centers, making stereochemistry irrelevant for its olfactory properties. Its relatively low molecular weight (158.24 g/mol) contributes to high volatility and strong odor impact.
Physical & Chemical Properties
| Boiling Point | 178-180 °C |
|---|---|
| Density | 0.862 g/cm³ |
| Refractive Index | 1.407-1.411 |
| Flash Point | 61 °C |
| Solubility | Slightly soluble in water, miscible with ethanol |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-1% | Up to 3% | Used sparingly for fruity top notes |
| Functional Fragrance | 0.5-2% | Up to 5% | Higher levels in soaps, detergents |
| Flavoring | 10-50 ppm | Up to 100 ppm | GRAS limits apply |
Classic Accords
Tip: Use with citrus oils to prevent excessive sweetness – bergamot works particularly well.
Alternatives & Comparisons
The acetate version offers a slightly greener, less sweet banana note with better diffusion in floral compositions.
Provides similar fruitiness but with more pear/apple character and less candy-like intensity.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted under IFRA standards. Listed in IFRA Transparency List with no usage limits.
RIFM Assessment
RIFM evaluation confirms safe use at current industry levels with no sensitization concerns.
Sustainability
As a purely synthetic material, isoamyl butyrate has minimal environmental impact in production. The esterification process is atom-efficient with high yields. No agricultural land use or biodiversity concerns exist as with natural fruit extracts. Being petroleum-derived, its carbon footprint depends on feedstock sourcing, but its extreme potency means very small quantities are used.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090866
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPerfumer’s Notes
FEMA #: 2060 | IOFI #: Nature Identical
Isoamyl butyrate has a fruity, apricot, pineapple, banana, strong, characteristic odor and a sweet, corresponding taste.
Odor: [‘fruity’]
MW: 158.24
LogP: 2.6
Ingredient Data Sheet
CAS 106-27-4Physical Properties
| Molecular Weight | 158.24 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 2.6🔬 PubChem |
| Boiling Point | 179 °C🔬 EPA CompTox |
| Vapor Pressure | 1.0501 mmHg @ 25°C📊 OPERA |
| Flash Point | 59 °C🔬 EPA CompTox |
| Involatility Index | 0.09💻 Calculated |
| log Kp (skin permeability) | -1.819💻 Calculated |
| SMILES | CCCC(=O)OCCC(C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Slow💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | fruity• leffingwell |
| Functional Groups | esterether💻 RDKit |
| “Powerful and diffusive fruity, sweet Apricot-Banana-Pineapple-like odor, somewhat sharper than that of the iso-Amyl-iso-butyrate.”📖 Arctander | |
| Isoamyl butyrate has a fruity, apricot, pineapple, banana, strong, characteristic odor and a sweet, corresponding taste.📖 Fenaroli | |
Flavor Notes (Arctander)
| “Extensively used in flavor compositions. This ester may constitute a large percentage of many fruit flavors, such as: imitation Apricot, Banana, Cherry, Peach, Strawberry, "Tutti-frutti", etc. and in Butter, Butterscotch, Chocolate, etc. Insoluble in water, soluble in alcohol, essential oils, perfum”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 0.5629 ppm (n=6)📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2060⚖️ 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: DTXSID3042059
Physical Properties
| Molecular Weight | 158.241 g/mol🔬 EPA CompTox |
| Density | 0.86 g/cm^3🔬 EPA CTX |
| Boiling Point | 179.4 °C🔬 EPA CTX |
| Melting Point | -73.1 °C🔬 EPA CTX |
| Flash Point | 58.15 °C🔬 EPA CTX |
| Refractive Index | 1.417 Dimensionless📊 OPERA |
| Molar Volume | 180.955 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.62 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 3.072 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.072 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.43 Log10 unitless📊 OPERA |
| Water Solubility | 0.001 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0.001 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 1.142 mmHg🔬 EPA CTX |
| Viscosity | 1.094 cP📊 OPERA |
| Surface Tension | 25.889 dyn/cm📊 OPERA |
| Thermal Conductivity | 132.267 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 | 5 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 45.478 cm^3/mol📊 OPERA |
| Polarizability | 18.029 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.
