Ethyl oct-2-enoate (CAS 2351-90-8) — Green Top to mid Note Fragrance Ingredient
Ethyl oct-2-enoate
CAS 2351-90-8
What Is Ethyl oct-2-enoate?
Ethyl oct-2-enoate is a synthetic fragrance ingredient used in perfumes and flavored products. It contributes a fruity, green aroma reminiscent of unripe apples or fresh-cut grass. This ester is found in various consumer products from fine fragrances to household cleaners, where it adds a crisp, natural character. As a versatile synthetic, it helps perfumers recreate the scent of fresh fruits without relying on seasonal harvests, making fragrances more consistent and sustainable year-round.
Safety Profile
GENERALLY SAFEWhat Does Ethyl oct-2-enoate Smell Like?
Ethyl oct-2-enoate bursts with the crispness of just-bitten Granny Smith apples, underscored by the faintly oily greenness of freshly mowed lawn. The opening is all sharp edges – like snapping a green bean in half – that gradually soften into the waxy sweetness of apple peel left in sunlight. As it dries, a subtle coconut nuance emerges, as if the fruitiness has been dipped in sunscreen. This transformation from tart to tropical makes it particularly useful for creating dynamic top notes that evolve intriguingly over the first hour of wear.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the crisp vegetal quality of the tea accord, creating the illusion of freshly brewed green tea leaves with an apple-like fruity lift that prevents the composition from becoming too austere.
Jean-Claude Ellena employs this material to construct the unripe mango effect, blending its green apple character with calone for an aqueous, just-picked fruit sensation that defines the fragrance’s opening.
2D Molecular Structure
SMILES: CCCCCC=CC(=O)OCC
Chemistry, Properties & Perfumer Guide
The Chemistry
Ethyl oct-2-enoate belongs to the α,β-unsaturated ester family, characterized by a carbon-carbon double bond adjacent to the ester carbonyl group. This structural feature contributes to its vibrant green character. Industrially produced through acid-catalyzed esterification of 2-octenoic acid with ethanol, the material typically exists as a mixture of E and Z isomers. The E isomer tends to dominate in commercial samples due to its greater thermodynamic stability, though some perfumers specifically seek out Z-rich batches for their sharper, more herbaceous qualities.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Approx. 200-205°C |
| Density | ~0.88 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Adds crisp top notes |
| Functional Fragrances | 0.1-0.5% | Up to 1% | Provides fresh green accents |
Classic Accords
Tip: Use to bridge citrus and floral notes in fresh compositions – its green fruitiness prevents sharp transitions.
Alternatives & Comparisons
When a richer, pear-like fruitiness is desired instead of green apple character. Longer lasting with similar molecular structure.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted under current IFRA standards (Amendment 49).
RIFM Assessment
Considered safe as used in current fragrance applications according to RIFM assessments.
Sustainability
As a purely synthetic material, ethyl oct-2-enoate avoids agricultural land use and seasonal variability. Production from petrochemical feedstocks raises carbon footprint concerns, but its high potency means relatively small quantities are needed. Some manufacturers are exploring bio-based routes using fermentation-derived alcohols and acids to improve sustainability.
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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: DTXSID5062344
Physical Properties
| Molecular Weight | 170.252 g/mol🔬 EPA CompTox |
| Density | 0.913 g/cm^3📊 OPERA |
| Boiling Point | 218.342 °C📊 OPERA |
| Melting Point | -21.979 °C📊 OPERA |
| Flash Point | 93.263 °C📊 OPERA |
| Refractive Index | 1.44 Dimensionless📊 OPERA |
| Molar Volume | 190.7 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.654 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.654 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.654 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.06 Log10 unitless📊 OPERA |
| Water Solubility | 0.002 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.115 mmHg📊 OPERA |
| Surface Tension | 28.34 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 | 6 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 50.21 cm^3/mol📊 OPERA |
| Polarizability | 19.905 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.
