Pentanoic acid, 2-methylbutyl ester (CAS 55590-83-5) — Sweet Top to middle Note Fragrance Ingredient
Pentanoic acid, 2-_methylbutyl ester
CAS 55590-83-5
What Is Pentanoic acid, 2-_methylbutyl ester?
Pentanoic acid, 2-methylbutyl ester is a synthetic fragrance compound primarily encountered in fine perfumes and body care products. It contributes fruity, apple-like nuances to fragrance compositions. This ingredient matters because it provides perfumers with a stable, consistent alternative to natural fruit esters, allowing for precise control over fruity accords without the variability of natural extracts.
Safety Profile
GENERALLY SAFEWhat Does Pentanoic acid, 2-_methylbutyl ester Smell Like?
This ester delivers a bright, juicy top note reminiscent of freshly cut green apples with a slight tropical undertone. The initial burst evolves into a more rounded, slightly boozy fruitiness akin to apple brandy or pear schnapps. In drydown, it leaves a clean, slightly waxy impression that blends well with other fruity and floral materials. The overall effect is energetic yet sophisticated, making it valuable for modern fruity-floral compositions.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to enhance the crisp apple note in this iconic summer fragrance, providing freshness that contrasts with the woody base. Its stability helps maintain the fruity character in the top-to-heart transition.
Contributes to the luminous fruity opening, blending with quince and jasmine to create a dewy, youthful effect. The ester’s moderate tenacity makes it ideal for this soft floral composition.
2D Molecular Structure
SMILES: CCCCC(=O)OCC(C)CC
Chemistry, Properties & Perfumer Guide
The Chemistry
A branched-chain ester formed through Fischer esterification of 2-methylbutanol with pentanoic acid. The branched structure lowers volatility compared to straight-chain counterparts while maintaining good diffusion. Industrial synthesis typically employs acid-catalyzed reactions under controlled conditions to maximize yield and purity. The chiral center at the 2-position can produce different olfactory nuances in enantiomeric forms.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | ~200 °C (estimated) |
| Density | ~0.86 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-3% | Up to 5% | Fruity modifier |
| Body Care | 0.1-1% | Up to 2% | Freshness booster |
Classic Accords
Tip: Use with citrus notes to enhance juiciness or with white musks to create shampoo-fresh effects.
Alternatives & Comparisons
Provides a more straightforward apple-pear character with higher volatility. Prefer when a sharper, shorter-lived fruity note is desired.
Offers a banana-like fruitiness with stronger diffusion. Better for tropical or candy-like compositions.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA standards.
RIFM Assessment
No specific RIFM assessment found; considered safe at current usage levels based on structural analogs.
Sustainability
Synthetic production allows for consistent quality with lower environmental impact than some natural fruit extracts. The manufacturing process can utilize green chemistry principles to minimize waste and energy use.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090772
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 55590-83-5Physical Properties
| Molecular Weight | 172.26 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 3.2🔬 PubChem |
| Boiling Point | 199 °C🔬 EPA CompTox |
| Vapor Pressure | 0.5495 mmHg @ 25°C📊 OPERA |
| Flash Point | 71.4 °C🔬 EPA CompTox |
| Involatility Index | 0.0451💻 Calculated |
| log Kp (skin permeability) | -1.479💻 Calculated |
| SMILES | CCCCC(=O)OCC(C)CC🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Slow💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | appleapricotbananafruity• leffingwell |
| Functional Groups | esterether💻 RDKit |
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: DTXSID50866491
Physical Properties
| Molecular Weight | 172.268 g/mol🔬 EPA CompTox |
| Density | 0.87 g/cm^3📊 OPERA |
| Boiling Point | 195.602 °C📊 OPERA |
| Melting Point | -66.969 °C📊 OPERA |
| Flash Point | 69.89 °C📊 OPERA |
| Refractive Index | 1.421 Dimensionless📊 OPERA |
| Molar Volume | 197.462 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.614 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.614 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.614 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.97 Log10 unitless📊 OPERA |
| Water Solubility | 0.002 mol/L📊 OPERA |
| Henry's Law Constant | 0.001 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.502 mmHg📊 OPERA |
| Viscosity | 1.281 cP📊 OPERA |
| Surface Tension | 26.178 dyn/cm📊 OPERA |
| Thermal Conductivity | 133.536 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 | 50.111 cm^3/mol📊 OPERA |
| Polarizability | 19.866 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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