Isobutyl 2-butenoate (CAS 589-66-2) — Citrus Top Note Fragrance Ingredient
Isobutyl 2-butenoate
CAS 589-66-2
What Is Isobutyl 2-butenoate?
Isobutyl 2-butenoate is a synthetic ester used in fruit-flavored fragrances and food flavorings. It imparts a fresh, apple-like scent with a hint of berry. Consumers encounter it in air fresheners, body sprays, and some fruity perfumes.
Safety Profile
GENERALLY SAFEWhat Does Isobutyl 2-butenoate Smell Like?
Isobutyl 2-butenoate offers a crisp, green apple top note with a juicy undercurrent reminiscent of ripe strawberries. The heart develops a subtle tartness like underripe raspberries, while the dry-down reveals a faintly woody, almost cider-like character. Its linear profile makes it ideal for creating persistent fruity accords.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as the primary apple note to create a realistic orchard effect, blending with pear and citrus for a sparkling top accord.
2D Molecular Structure
SMILES: CC=CC(=O)OCC(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
Isobutyl 2-butenoate belongs to the ester class, formed via Fischer esterification between isobutanol and 2-butenoic acid. Its compact molecular structure (C8H14O2) contributes to high volatility and moderate water solubility. The trans-configuration of the butenoate moiety enhances fruity character.
Physical & Chemical Properties
| Boiling Point | 142-144 °C |
|---|---|
| Density | 0.875 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Fruity top note |
| Functional Fragrance | 1-3% | Up to 10% | Air fresheners |
Classic Accords
Tip: Stabilize with antioxidants to prevent discoloration in citrus blends.
Alternatives & Comparisons
More banana-like, used when a sweeter fruit note is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted under current IFRA standards.
RIFM Assessment
RIFM assessment confirms safe use at reported levels.
Sustainability
Synthesized from petrochemical feedstocks with moderate environmental impact. Biodegradation studies show >80% degradation in 28 days.
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References
- PubChem Compound Summary for Isobutyl 2-butenoate CID 11269
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID7047691
Physical Properties
| Molecular Weight | 142.198 g/mol🔬 EPA CompTox |
| Density | 0.89 g/cm^3🔬 EPA CTX |
| Boiling Point | 171 °C🔬 EPA CTX |
| Melting Point | -41.186 °C📊 OPERA |
| Flash Point | 56.018 °C📊 OPERA |
| Refractive Index | 1.431 Dimensionless📊 OPERA |
| Molar Volume | 158.063 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.547 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.547 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.547 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.89 Log10 unitless📊 OPERA |
| Water Solubility | 0.062 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 1.542 mmHg📊 OPERA |
| Surface Tension | 26.383 dyn/cm📊 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 | 40.903 cm^3/mol📊 OPERA |
| Polarizability | 16.215 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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