2-Methylpropyl 2-methylbutyrate (CAS 2445-67-2) — Sweet Top Note Fragrance Ingredient
2-Methylpropyl 2-methylbutyrate
CAS 2445-67-2
What Is 2-Methylpropyl 2-methylbutyrate?
2-Methylpropyl 2-methylbutyrate is a synthetic fragrance ingredient used in perfumes and flavored products. It’s often found in fruity or tropical scented items like body sprays, candles, and food flavorings. This ester compound matters because it adds a juicy, apple-like freshness to fragrances while being more stable than some natural alternatives. Its controlled synthesis allows for consistent quality in mass-produced scents.
Safety Profile
GENERALLY SAFEWhat Does 2-Methylpropyl 2-methylbutyrate Smell Like?
This ester bursts with a crisp, green apple top note that’s slightly tart yet sweet, like biting into a just-ripe Granny Smith. The heart develops a creamier nuance reminiscent of pear skins and banana peel, while the dry-down reveals a faint woody undertone. It maintains remarkable freshness throughout evaporation, behaving like nature’s own fruit cocktail with a synthetic precision that natural extracts can’t match.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as the primary apple accord, providing photostable fruity top notes that last longer than natural extracts in this single-note fragrance.
Blended with coconut and passionfruit notes to create a synthetic-yet-naturalistic tropical fruit cocktail effect in body sprays.
2D Molecular Structure
SMILES: CCC(C)C(=O)OCC(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Methylpropyl 2-methylbutyrate belongs to the ester class, formed through esterification of 2-methylbutyric acid with isobutanol. While not found in nature, its structure mimics fruit-derived esters. Industrial synthesis typically employs acid-catalyzed Fischer esterification under controlled conditions. The branched alkyl groups create steric hindrance that contributes to its unique volatility profile and resistance to hydrolysis compared to straight-chain esters.
Physical & Chemical Properties
| Appearance | Colorless liquid |
|---|---|
| Odor Threshold | 0.1 ppm in air |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Fruity top note enhancer |
| Body Care | 0.1-1% | Up to 3% | Shower gels and shampoos |
Classic Accords
Tip: Stabilize with antioxidants to prevent ester degradation in alkaline formulations.
Alternatives & Comparisons
More volatile with sharper green notes, better for fleeting top notes but lacks the creamy depth of the isobutyl variant.
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
Not yet fully assessed by RIFM, but preliminary data suggests low sensitization potential.
Sustainability
As a synthetic material, production avoids agricultural land use but depends on petrochemical feedstocks. The esterification process generates minimal waste when optimized. Future green chemistry approaches may enable bio-based synthesis from fermented sugars.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090869
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID20862945
Physical Properties
| Molecular Weight | 158.241 g/mol🔬 EPA CompTox |
| Density | 0.869 g/cm^3📊 OPERA |
| Boiling Point | 166.149 °C📊 OPERA |
| Melting Point | -65.736 °C📊 OPERA |
| Flash Point | 50.711 °C📊 OPERA |
| Refractive Index | 1.415 Dimensionless📊 OPERA |
| Molar Volume | 181.332 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.043 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.043 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.043 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.56 Log10 unitless📊 OPERA |
| Water Solubility | 0.006 mol/L📊 OPERA |
| Henry's Law Constant | 0.001 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 1.953 mmHg📊 OPERA |
| Viscosity | 1.069 cP📊 OPERA |
| Surface Tension | 25.013 dyn/cm📊 OPERA |
| Thermal Conductivity | 126.469 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 | 45.437 cm^3/mol📊 OPERA |
| Polarizability | 18.013 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.
