2-Methylbutanol (CAS 137-32-6) — Sweet Top to middle Note Fragrance Ingredient
2-Methylbutanol
CAS 137-32-6
What Is 2-Methylbutanol?
2-Methylbutanol is a synthetic alcohol used in perfumery for its fruity, fermented aroma. You’ll encounter it in fine fragrances and flavorings. This ingredient adds depth to fruity compositions and enhances the naturalness of berry and tropical fruit accords.
Safety Profile
GENERALLY SAFEWhat Does 2-Methylbutanol Smell Like?
2-Methylbutanol presents a complex olfactory profile that evolves from an initial sharp, fermented fruit character reminiscent of overripe bananas and pineapple rind. As it settles, the heart reveals a warmer, whiskey-like nuance with hints of caramelized sugar. The dry-down is surprisingly clean, leaving a subtle musky-fruity trail that blends seamlessly with woody base notes. Its behavior resembles a lighter version of fusel oils, offering perfumers a controlled way to introduce fermented complexity without overwhelming compositions.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to enhance the tropical fruit accord, adding a fermented depth that makes the mango and cardamom notes feel more natural and dimensional.
Contributes to the mysterious fruity-chocolate accord, bridging the gap between the bright top notes and deep base with its fermented character.
2D Molecular Structure
SMILES: CCC(C)CO
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Methylbutanol belongs to the family of short-chain branched alcohols. While it can occur naturally in some fermented products, the perfumery version is typically synthesized through hydroformylation of butene followed by hydrogenation. Its branched structure gives it different volatility and odor characteristics compared to straight-chain pentanols. The molecule exists in two enantiomeric forms, with the (S)-enantiomer being more common in nature and generally perceived as more pleasant.
Physical & Chemical Properties
| Boiling Point | 128-130 °C |
|---|---|
| Density | 0.815 g/cm³ |
| Refractive Index | 1.409 |
| Flash Point | 40 °C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Fruity modifier |
| Functional Fragrance | 0.1-0.5% | Up to 1% | Complexity enhancer |
Classic Accords
Tip: Use sparingly in floral compositions to add natural fermentation nuances that prevent flowers from smelling too clean or synthetic.
Alternatives & Comparisons
More intense fermented character, useful when a stronger whiskey-like note is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions apply to 2-Methylbutanol.
GHS Classification
RIFM Assessment
RIFM has evaluated 2-Methylbutanol and found it safe for current usage levels in fragrance applications.
Sustainability
As a synthetic material, 2-Methylbutanol production doesn’t rely on agricultural resources. Modern synthesis routes have improved energy efficiency and reduced waste compared to traditional methods. Its relatively low usage levels in formulations contribute to minimal environmental impact.
Explore 2-Methylbutanol
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090867
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 137-32-6Physical Properties
| Molecular Weight | 88.15 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.2🔬 PubChem |
| Boiling Point | 128 °C🔬 EPA CompTox |
| Vapor Pressure | 3.12 mmHg @ 25°C📊 OPERA |
| Flash Point | 50 °C🔬 EPA CompTox |
| Involatility Index | 0.3582💻 Calculated |
| log Kp (skin permeability) | -2.386💻 Calculated |
| SMILES | CCC(C)CO🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Moderate💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | alcoholicetherealsolvent• leffingwell |
| Functional Groups | alcohol💻 RDKit |
| (+/–)2-Methyl-1-butanol has a cooked, roasted aroma with fruity or alcoholic undernotes.📖 Fenaroli | |
Sensory Thresholds
| Odor Detection Threshold | 3.5675 ppm (n=8)📖 van Gemert |
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: DTXSID5027069
Physical Properties
| Molecular Weight | 88.15 g/mol🔬 EPA CompTox |
| Density | 0.812 g/cm^3🔬 EPA CTX |
| Boiling Point | 128.214 °C🔬 EPA CTX |
| Melting Point | -46.25 °C🔬 EPA CTX |
| Flash Point | 45.79 °C🔬 EPA CTX |
| Refractive Index | 1.405 Dimensionless📊 OPERA |
| Molar Volume | 108.952 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.273 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 1.214 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.214 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.51 Log10 unitless📊 OPERA |
| Water Solubility | 0.338 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 2.976 mmHg🔬 EPA CTX |
| Viscosity | 3.282 cP📊 OPERA |
| Surface Tension | 25.302 dyn/cm📊 OPERA |
| Thermal Conductivity | 143.801 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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