Ethyl 2-methylpentanoate (CAS 39255-32-8) — Sweet Top Note Fragrance Ingredient
Ethyl 2-methylpentanoate
CAS 39255-32-8
What Is Ethyl 2-methylpentanoate?
Ethyl 2-methylpentanoate is a synthetic ester used in fruity fragrance compositions. You’ll encounter it in body care products and some fresh, modern perfumes. This ingredient matters because it adds a crisp, juicy character to fragrances, helping create realistic fruit notes without relying on natural extracts that may vary in quality.
Safety Profile
GENERALLY SAFEWhat Does Ethyl 2-methylpentanoate Smell Like?
Ethyl 2-methylpentanoate bursts with a vibrant, green apple peel freshness that evolves into a juicy pear-like sweetness. The top note has a crisp, almost effervescent quality reminiscent of just-cut tropical fruit. As it dries down, it reveals a softer, more rounded character with hints of ripe melon and a whisper of pineapple. The dry-out maintains a clean fruitiness without becoming cloying, making it excellent for modern fresh fragrances.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to enhance the crisp top notes, contributing to the fragrance’s signature fresh-cut grass and citrus opening with a subtle fruity undertone.
Provides a juicy apple-like accent to the citrus opening, reinforcing the Mediterranean freshness theme.
2D Molecular Structure
SMILES: CCCC(C)C(=O)OCC
Chemistry, Properties & Perfumer Guide
The Chemistry
Ethyl 2-methylpentanoate belongs to the ester class, synthesized through esterification of 2-methylpentanoic acid with ethanol. Its branched carbon chain creates steric hindrance that influences both volatility and odor characteristics. The asymmetric carbon at position 2 means it exists as enantiomers, though commercial material is typically racemic. Industrial synthesis often employs acid-catalyzed Fischer esterification or enzymatic methods for higher purity.
Physical & Chemical Properties
| Appearance | Colorless liquid |
|---|---|
| Boiling Point | ~165-170°C (estimated) |
| Density | ~0.86 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-3% | Up to 5% | Fresh top note component |
| Body Care | 0.1-1% | Up to 2% | Fruity freshness booster |
Classic Accords
Tip: Use with citrus oils to create sparkling fruity-citrus openings.
Alternatives & Comparisons
More intense apple character with higher volatility, useful when stronger top impact is needed.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions currently apply to this material.
RIFM Assessment
Considered safe for current fragrance use levels based on structural analogs.
Sustainability
As a synthetic material, ethyl 2-methylpentanoate offers consistent quality without agricultural inputs. Production typically uses petrochemical feedstocks, though bio-based routes from fermented sugars are being explored. Its efficient synthesis and low usage levels make it relatively sustainable compared to some natural fruit extracts.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID7047198
Physical Properties
| Molecular Weight | 144.214 g/mol🔬 EPA CompTox |
| Density | 0.836 g/cm^3🔬 EPA CTX |
| Boiling Point | 156 °C🔬 EPA CTX |
| Melting Point | -71.312 °C📊 OPERA |
| Flash Point | 43.5 °C🔬 EPA CTX |
| Refractive Index | 1.411 Dimensionless📊 OPERA |
| Molar Volume | 164.448 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.09 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 2.506 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.506 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.94 Log10 unitless📊 OPERA |
| Water Solubility | 0.003 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 4.374 mmHg🔬 EPA CTX |
| Viscosity | 0.934 cP📊 OPERA |
| Surface Tension | 25.239 dyn/cm📊 OPERA |
| Thermal Conductivity | 132.106 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 | 4 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 40.845 cm^3/mol📊 OPERA |
| Polarizability | 16.192 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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