Ethyl trans-2-butenoate (CAS 10544-63-5) — Citrus Top Note Fragrance Ingredient
Ethyl trans-2-butenoate
CAS 10544-63-5
What Is Ethyl trans-2-butenoate?
Ethyl trans-2-butenoate is a synthetic ester used in perfumery to create fruity, fresh, and slightly green aromas. You might encounter it in citrusy or tropical fragrances, where it adds a crisp, juicy character. This ingredient matters because it helps perfumers achieve realistic fruit notes without relying on natural extracts, which can vary in quality and availability. Its clean, bright profile makes it versatile for modern fresh fragrances.
Safety Profile
GENERALLY SAFEWhat Does Ethyl trans-2-butenoate Smell Like?
Ethyl trans-2-butenoate bursts with a vibrant, green-fruity character reminiscent of unripe strawberries and freshly cut apples. The top note is sharp and slightly tart, like the first bite of a green pear, evolving into a softer, juicier heart with hints of melon rind. As it dries down, it leaves a clean, slightly waxy impression, like the skin of a just-washed grape. The overall effect is crisp and refreshing, with none of the cloying sweetness found in heavier fruit esters.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the bitter citrus opening, adding a dewy greenness that makes the lemon note smell freshly squeezed rather than candied.
Provides the wet, rain-soaked melon effect in this monsoon-inspired composition, blending seamlessly with aquatic notes.
2D Molecular Structure
SMILES: CCOC(=O)C=CC
Chemistry, Properties & Perfumer Guide
The Chemistry
Ethyl trans-2-butenoate belongs to the ester class, specifically unsaturated aliphatic esters. It’s synthesized via esterification of trans-2-butenoic acid with ethanol, typically using acid catalysis. The trans configuration at the double bond contributes to its sharper, greener odor profile compared to its cis isomer. While not found in significant quantities in nature, related esters occur in various fruits, explaining its convincing fruity character.
Physical & Chemical Properties
| Boiling Point | Estimated 145-150°C |
|---|---|
| Density | Approx. 0.92 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Fresh top note modifier |
| Functional Fragrance | 0.1-0.5% | Up to 1% | Clean fruity lift |
Classic Accords
Tip: Use to add crispness to citrus blends or to prevent fruity notes from becoming too sweet.
Alternatives & Comparisons
The cis isomer has a softer, riper fruit character when a less green effect is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions currently apply to this material.
RIFM Assessment
Not currently evaluated by RIFM, but structurally similar esters have good safety profiles.
Sustainability
As a synthetic material, ethyl trans-2-butenoate offers consistent quality with minimal environmental impact from production. It reduces reliance on natural fruit extracts that may have agricultural supply chain issues. The synthesis uses common petrochemical feedstocks with established recycling pathways for byproducts.
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References
- Bauer et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID8065119
Physical Properties
| Molecular Weight | 114.144 g/mol🔬 EPA CompTox |
| Density | 0.93 g/cm^3📊 OPERA |
| Boiling Point | 136.537 °C📊 OPERA |
| Melting Point | -1.435 °C📊 OPERA |
| Flash Point | 28.375 °C🔬 EPA CTX |
| Refractive Index | 1.422 Dimensionless📊 OPERA |
| Molar Volume | 124.673 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.698 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 1.698 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.698 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.36 Log10 unitless📊 OPERA |
| Water Solubility | 0.09 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 7.601 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 | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 31.679 cm^3/mol📊 OPERA |
| Polarizability | 12.558 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.
