Isopropyl 2-methylbutyrate (CAS 66576-71-4) — Sweet Top Note Fragrance Ingredient
Isopropyl 2-methylbutyrate
CAS 66576-71-4
What Is Isopropyl 2-methylbutyrate?
Isopropyl 2-methylbutyrate is a synthetic ester commonly used in fruity and apple-like fragrance compositions. You encounter it in body sprays, shampoos, and air fresheners. This molecule matters because it provides a cost-effective, stable alternative to natural fruit extracts, allowing consistent quality across mass-market products.
Safety Profile
GENERALLY SAFEWhat Does Isopropyl 2-methylbutyrate Smell Like?
A burst of freshly cut green apples with a slight fermented undertone – think cider house floors after pressing season. The top note has a fizzy, almost effervescent quality that settles into a deeper, rum-like sweetness. Over hours, it reveals a subtle woody backbone that prevents cloyingness, making it useful for masculine fruity accords.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Provides the crisp apple peel effect in this iconic fragrance, blending with rosewood to create a contemporary fruity-floral signature.
Used in the synthetic apple accord that contrasts with spicy pink pepper, demonstrating its versatility in masculine compositions.
2D Molecular Structure
SMILES: CCC(C)C(=O)OC(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
An ester formed from isopropanol and 2-methylbutyric acid. Industrially produced via acid-catalyzed esterification. The branched structure enhances volatility while the ester linkage provides stability against hydrolysis compared to straight-chain counterparts. Often used as a racemic mixture though chiral forms exist.
Physical & Chemical Properties
| Molecular Weight | 144.21 g/mol |
|---|---|
| Boiling Point | 142-144 °C |
| Density | 0.865 g/cm³ (20°C) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Functional Fragrances | 0.5-2% | Up to 5% | Provides fruity lift in detergents |
| Fine Fragrance | 0.1-0.8% | Up to 1.2% | Used in modern fruity top notes |
Classic Accords
Tip: Combine with ionones to extend fruity character into heart phase.
Alternatives & Comparisons
More diffusive but less tenacious. Preferred when brighter top notes are needed.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No restrictions under current IFRA standards.
RIFM Assessment
RIFM-reviewed with no safety concerns at current use levels.
Sustainability
Synthesized from petrochemical feedstocks but requires less agricultural land than natural apple extracts. Energy-intensive production offset by high odor potency enabling low dosage.
Explore Isopropyl 2-methylbutyrate
Browse essential oils and aroma compounds.
Browse on iHerb →Affiliate disclosure: we may earn a small commission at no extra cost to you.
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 errorPhysicochemical Properties
DTXSID: DTXSID3047550
Physical Properties
| Molecular Weight | 144.214 g/mol🔬 EPA CompTox |
| Density | 0.851 g/cm^3🔬 EPA CTX |
| Boiling Point | 143.384 °C📊 OPERA |
| Melting Point | -72.042 °C📊 OPERA |
| Flash Point | 34.736 °C📊 OPERA |
| Refractive Index | 1.41 Dimensionless📊 OPERA |
| Molar Volume | 164.825 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.447 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.447 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.447 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.87 Log10 unitless📊 OPERA |
| Water Solubility | 0.011 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 5.466 mmHg📊 OPERA |
| Viscosity | 0.936 cP📊 OPERA |
| Surface Tension | 24.775 dyn/cm📊 OPERA |
| Thermal Conductivity | 125.865 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 | 3 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 40.804 cm^3/mol📊 OPERA |
| Polarizability | 16.176 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.
