n-Butyl 2-methylbutyrate (CAS 15706-73-7) — Sweet Top Note Fragrance Ingredient
n-Butyl 2-methylbutyrate
CAS 15706-73-7
What Is n-Butyl 2-methylbutyrate?
n-Butyl 2-methylbutyrate is a synthetic ester used in fruity flavorings and fragrances. You’ll encounter it in candies, beverages, and some tropical-inspired perfumes. This ingredient matters because it delivers a potent, natural-smelling fruitiness that’s more stable than actual fruit extracts, allowing consistent quality in mass-produced products.
Safety Profile
GENERALLY SAFEWhat Does n-Butyl 2-methylbutyrate Smell Like?
A burst of overripe pineapple and banana peel dominates the opening, with a juicy, almost fermented quality. As it settles, the sweetness mellows into something resembling warm apple cider with a hint of rum. The dry-down reveals a faint waxy undertone, like the skin of unwashed grapes left in the sun.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the coconut-lime cocktail illusion, contributing a boozy tropical fruit nuance that blends seamlessly with the citrus top notes.
Provides a counterpoint to the bitter orange with its fermented fruit character, creating depth in what might otherwise be a simple citrus composition.
2D Molecular Structure
SMILES: CCCCOC(=O)C(C)CC
Chemistry, Properties & Perfumer Guide
The Chemistry
This branched-chain ester belongs to the class of aliphatic carboxylic acid esters. Synthesized via Fischer esterification of 2-methylbutyric acid with n-butanol, typically using acid catalysis. The branched structure increases volatility compared to straight-chain esters while maintaining good tenacity. No chirality concerns as the 2-methyl group creates only one stereocenter.
Physical & Chemical Properties
| Boiling Point | ~175-180 °C (estimated) |
|---|---|
| Density | ~0.87 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Tropical fruit effects |
| Functional Fragrance | 0.1-0.5% | Up to 1% | Shampoos, soaps |
Classic Accords
Tip: Use with citrus top notes to create dimensionality in tropical compositions.
Alternatives & Comparisons
More volatile with sharper fruitiness, better for fleeting top notes when a quicker evaporation is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions
RIFM Assessment
Evaluated as safe for current use levels in fragrance applications.
Sustainability
Synthetic production avoids agricultural land use. Typical synthesis from petrochemical feedstocks raises some environmental concerns, but newer routes from bio-based 2-methylbutyric acid are being developed. Biodegradability expected to be moderate based on ester structure.
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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: DTXSID4047046
Physical Properties
| Molecular Weight | 158.241 g/mol🔬 EPA CompTox |
| Density | 0.86 g/cm^3🔬 EPA CTX |
| Boiling Point | 179 °C🔬 EPA CTX |
| Melting Point | 175 °C🔬 EPA CTX |
| Flash Point | 59.639 °C📊 OPERA |
| Refractive Index | 1.417 Dimensionless📊 OPERA |
| Molar Volume | 180.955 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.072 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.072 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.072 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.43 Log10 unitless📊 OPERA |
| Water Solubility | 0.004 mol/L📊 OPERA |
| Henry's Law Constant | 0.001 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 1.213 mmHg📊 OPERA |
| Viscosity | 1.115 cP📊 OPERA |
| Surface Tension | 25.725 dyn/cm📊 OPERA |
| Thermal Conductivity | 132.691 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 | 5 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 45.478 cm^3/mol📊 OPERA |
| Polarizability | 18.029 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.
