Butanoic acid, 2-methyl-, pentyl ester (CAS 68039-26-9) — Sweet Top Note Fragrance Ingredient
Butanoic acid, 2-methyl-, pentyl ester
CAS 68039-26-9
What Is Butanoic acid, 2-methyl-, pentyl ester?
Butanoic acid, 2-methyl-, pentyl ester is a synthetic fragrance compound used to create fruity, apple-like scents in perfumes and flavored products. You’ll encounter it in body care items, candles, and some food flavorings. This ester matters because it adds a crisp, juicy top note that blends well with other fruity and floral ingredients, helping create lifelike fruit accords without using natural extracts.
Safety Profile
GENERALLY SAFEWhat Does Butanoic acid, 2-methyl-, pentyl ester Smell Like?
A burst of ripe, juicy apples with a candy-like sweetness dominates the first impression. The scent evolves into a slightly tropical undertone reminiscent of pineapple skin. As it dries down, a faint dairy creaminess emerges, rounding out the fruitiness. The overall effect is like biting into a just-ripe Fuji apple with a whisper of banana in the background.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as the primary apple note, creating a crisp alcoholic impression that mimics the bite of fine Calvados.
Provides a subtle fruity lift to the citrus-green tea accord, adding dimension without overpowering.
2D Molecular Structure
SMILES: CCCCCOC(=O)C(C)CC
Chemistry, Properties & Perfumer Guide
The Chemistry
This branched-chain ester belongs to the fruit ester family, created through Fischer esterification of 2-methylbutanoic acid with pentanol. The methyl group branching creates chirality, with the (S)-enantiomer being more potent. Industrial synthesis typically produces racemic mixtures. Unlike straight-chain esters, the branching gives it greater stability against hydrolysis in formulations.
Physical & Chemical Properties
| Appearance | Colorless liquid |
|---|---|
| Molecular Weight | 158.24 g/mol |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-3% | Up to 5% | Fruity top note |
| Candles | 1-4% | Up to 8% | Heat-stable fruit note |
Classic Accords
Tip: Use with bergamot and hedione to create a sparkling fruit cocktail effect.
Alternatives & Comparisons
Similar profile with slightly greener, less sweet character and better longevity.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions (2023 Amendment 51)
RIFM Assessment
Considered safe for current usage levels based on RIFM’s 2018 evaluation.
Sustainability
Synthetic production from petrochemical precursors has moderate environmental impact. No known biotechnology routes yet exist. The ester’s stability reduces need for frequent reapplication in products, indirectly lowering environmental load versus more volatile alternatives.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781439847503
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID50867443
Physical Properties
| Molecular Weight | 172.268 g/mol🔬 EPA CompTox |
| Density | 0.871 g/cm^3📊 OPERA |
| Boiling Point | 196.41 °C📊 OPERA |
| Melting Point | -67.568 °C📊 OPERA |
| Flash Point | 70.876 °C📊 OPERA |
| Refractive Index | 1.421 Dimensionless📊 OPERA |
| Molar Volume | 197.462 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.786 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.786 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.786 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.97 Log10 unitless📊 OPERA |
| Water Solubility | 0.001 mol/L📊 OPERA |
| Henry's Law Constant | 0.001 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.386 mmHg📊 OPERA |
| Viscosity | 1.305 cP📊 OPERA |
| Surface Tension | 26.174 dyn/cm📊 OPERA |
| Thermal Conductivity | 133.968 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.
