Isoamyl alcohol (CAS 123-51-3) — Fruity Top Note Fragrance Ingredient
Isoamyl alcohol
CAS 123-51-3
What Is Isoamyl alcohol?
Isoamyl alcohol is a fruity-smelling alcohol used in many food flavorings and perfumes. You’ll encounter it in banana-flavored candies, fruit gums, and some floral fragrances. This ingredient matters because it provides a natural-smelling banana or pear note without using actual fruit extracts, making fragrances and flavors more consistent and shelf-stable.
Safety Profile
GENERALLY SAFEWhat Does Isoamyl alcohol Smell Like?
Isoamyl alcohol bursts with an intense, almost artificial banana candy aroma – think Runts candies or banana Laffy Taffy. The initial blast mellows into a softer, more rounded pear-like sweetness with a slight alcoholic warmth. As it dries down, it leaves a faintly waxy, floral trace that blends well with other fruity notes. The overall effect is playful and slightly tropical, though it can smell boozy if not properly balanced.
Scent Profile
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the candied fruit accord, giving the opening its distinctive banana-like sweetness that contrasts with the spicy heart notes.
Provides a fruity lift to the gourmand chocolate-coffee base, creating a playful contrast against the darker notes.
Adds a subtle tropical fruit nuance to the citrus top notes, enhancing the summer vacation vibe.
Contributes to the addictive candy-like quality of the vanilla-coffee accord, making it more playful and youthful.
Used sparingly to sweeten the pear top note, adding dimension to the fruity-floral opening.
2D Molecular Structure
SMILES: CC(C)CCO
Chemistry, Properties & Perfumer Guide
The Chemistry
Isoamyl alcohol (3-methyl-1-butanol) is a primary alcohol with a branched five-carbon structure. While it occurs naturally in fusel oils during fermentation, most commercial material is synthesized via the oxo process from isobutene or through hydrogenation of isovaleraldehyde. The molecule’s branching gives it different properties than straight-chain pentanol, including higher volatility and a more pronounced fruity odor. It exists as a racemic mixture in synthetic form, though some chiral separation occurs in natural sources.
Physical & Chemical Properties
| Boiling Point | 131-132 °C |
|---|---|
| Density | 0.8104 g/cm³ at 20°C |
| Refractive Index | 1.4055 at 20°C |
| Flash Point | 43 °C (closed cup) |
| Solubility | 25 g/L in water at 20°C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-3% | Up to 5% | Adds fruity lift to top notes |
| Food Flavoring | 10-100 ppm | Up to 200 ppm | Banana and pear flavor enhancer |
| Soap/Candle | 0.1-1% | Up to 2% | Use lower levels due to volatility |
| Household Products | 0.05-0.5% | Up to 1% | Adds fruity freshness to cleaners |
Classic Accords
Tip: Blend with green notes to temper the candy-like sweetness and add sophistication.
Alternatives & Comparisons
Less sweet and more solvent-like, useful when a subtler fruity note is needed. Has higher flash point for safer handling in industrial applications.
Longer-lasting with a greener, more natural fruit character. Better for floral compositions needing sustained fruity support.
Natural alternative with complex nuances, though less consistent in odor profile. Preferred for natural claims and artisanal applications.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. IFRA, REACH, EU Cosmetics Regulation standards update periodically. Consult current IFRA Standards Library before formulating. Not legal or regulatory advice.
IFRA Status
Not restricted under current IFRA standards (49th Amendment).
GHS Classification
RIFM Assessment
RIFM safety assessment confirms safe use at current industry levels in fragrances (2015 evaluation).
Sustainability
Most isoamyl alcohol is petroleum-derived, though some is produced from renewable resources via fermentation. The synthetic route has higher carbon footprint but offers greater purity and consistency. New bio-based production methods using agricultural waste streams are under development to improve sustainability.
Explore Isoamyl alcohol
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090772
- Opdyke, D.L. (1979). Monographs on fragrance raw materials: Isoamyl alcohol. Food and Cosmetics Toxicology, 17(5), 533-535. DOI:10.1016/0015-6264(79)90169-2
- PubChem Compound Summary for CID 31260 (Isoamyl alcohol). PubChem CID 31260
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Mar 2026.
Report a data errorIngredient Data Sheet
CAS 123-51-3Physical Properties
| Molecular Weight | 88.15 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.2🔬 PubChem |
| Boiling Point | 132.2 °C🔬 EPA CompTox |
| Vapor Pressure | 28 mmHg @ 25°C📊 OPERA |
| Flash Point | 45.6 °C🔬 EPA CompTox |
| Involatility Index | 3.2142💻 Calculated |
| log Kp (skin permeability) | -2.386💻 Calculated |
| SMILES | CC(C)CCO🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Very fast💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | alcoholic• leffingwell |
| Functional Groups | alcohol💻 RDKit |
| “Choking, disagreeable, cough-provoking, somewhat alcoholic odor, only in high dilution becoming pleasant, fruity-winey.”📖 Arctander | |
| Isoamyl alcohol has a fusel oil, whiskey-characteristic pungent odor and repulsive taste.📖 Fenaroli | |
Flavor Notes (Arctander)
| “NOTE: The name "Amyl alcohol" and the name "iso-Amyl alcohol" are used in perfume and flavor trade with little respect to the identity or true chemical name of the material. Much confusion still exists, particularly since Amyl alcohol made from Fusel oil is slowly disappearing from the American mark”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 7.8287 ppm (n=35)📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2057⚖️ 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: DTXSID3025469
Physical Properties
| Molecular Weight | 88.15 g/mol🔬 EPA CompTox |
| Density | 0.807 g/cm^3🔬 EPA CTX |
| Boiling Point | 131.084 °C🔬 EPA CTX |
| Melting Point | -111.19 °C🔬 EPA CTX |
| Flash Point | 44.475 °C🔬 EPA CTX |
| Refractive Index | 1.405 Dimensionless📊 OPERA |
| Molar Volume | 108.952 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.215 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 1.149 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.149 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.52 Log10 unitless🔬 EPA CTX |
| Water Solubility | 0.304 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 6.072 mmHg🔬 EPA CTX |
| Viscosity | 3.156 cP📊 OPERA |
| Surface Tension | 25.221 dyn/cm📊 OPERA |
| Thermal Conductivity | 143.255 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 20.23 Ų💻 Computed |
| H-Bond Donors | 1 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 26.707 cm^3/mol📊 OPERA |
| Polarizability | 10.587 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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