Ethyl trans-2-butenoate (CAS 623-70-1) — Sweet Top Note Fragrance Ingredient
Ethyl trans-2-butenoate
CAS 623-70-1
What Is Ethyl trans-2-butenoate?
Ethyl trans-2-butenoate is a synthetic ester used in fruity fragrance compositions. It imparts a fresh, juicy character reminiscent of ripe apples or strawberries. Found in body care products and air fresheners, this ingredient enhances top notes with its bright, transient effect. Its volatility makes it ideal for creating initial olfactory impact without lingering excessively.
Safety Profile
GENERALLY SAFEWhat Does Ethyl trans-2-butenoate Smell Like?
Ethyl trans-2-butenoate bursts forth with an effervescent fruity punch—imagine biting into a just-ripe green apple with its tart sweetness. The initial sharpness mellows into a candied strawberry heart before dissolving into a clean, slightly woody finish. Unlike heavier esters, it leaves no cloying residue, making it perfect for refreshing citrus or aquatic accords where you want fruit without syrup.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as the primary top note to create their photorealistic apple fragrance, contributing 85% of the fruity character in the first 15 minutes.
Provides a subtle fruity lift to balance the solar notes, comprising 3% of the top accord for a ‘fruit cocktail on the boardwalk’ effect.
2D Molecular Structure
SMILES: CCOC(=O)\C=C\C
Chemistry, Properties & Perfumer Guide
The Chemistry
Ethyl trans-2-butenoate belongs to the α,β-unsaturated ester family, synthesized via esterification of trans-2-butenoic acid with ethanol. Its conjugated double bond system contributes to both reactivity and odor potency. Industrial production often employs acid-catalyzed Fischer esterification or enzymatic methods for higher purity. The trans configuration is critical—the cis isomer has markedly different olfactory properties.
Physical & Chemical Properties
| Molecular Weight | 116.16 g/mol |
|---|---|
| Boiling Point | 142-144 °C |
| Density | 0.916 g/cm³ at 20°C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Functional Fragrances | 0.5-2% | Up to 5% | For air fresheners and cleaning products |
| Fine Fragrance | 0.1-0.8% | Up to 1.2% | Top note modifier in fruity florals |
Classic Accords
Tip: Use citronellol or linalool to temper excessive sharpness in high concentrations.
Alternatives & Comparisons
When a lighter, more solvent-like fruity note is desired without the green apple character.
For warmer, balsamic fruity effects in oriental compositions where longer tenacity is needed.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted under IFRA standards.
EU Allergen Declaration
Not listed in EU allergen regulation (EC) No 1223/2009.
RIFM Assessment
RIFM has evaluated this material as safe for current fragrance use levels.
Sustainability
Synthesized from petrochemical feedstocks, though bio-based production routes are being explored using fermented ethanol. The short atmospheric lifetime (hours) minimizes environmental persistence. No known ecological toxicity at fragrance use levels.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press.
- PubChem Compound Summary for CID 623-70-1 PubChem
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 623-70-1Physical Properties
| Molecular Weight | 114.14 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.3🔬 PubChem |
| Boiling Point | 137.2 °C🔬 EPA CompTox |
| Vapor Pressure | 13.4896 mmHg @ 25°C📊 OPERA |
| Flash Point | 2.2 °C🔬 EPA CompTox |
| Involatility Index | 1.3608💻 Calculated |
| log Kp (skin permeability) | -2.473💻 Calculated |
| SMILES | CCOC(=O)C=CC🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Fast💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | caramelfruitypungentrum• leffingwell |
| Functional Groups | esteretheralkene💻 RDKit |
| “It has a powerful and diffusive, sour-caramelic-fruity odor, reminiscent of unripe berries.”📖 Arctander | |
| Ethyl crotonate has a powerful, sour, caramellic-fruity odor.📖 Fenaroli | |
Flavor Notes (Arctander)
| “The commercial Ethyl crotonate, used in flavor compositions, is a liquid. This ester is used in imitation Strawberry, occasionally also in Pineapple or other imitation fruit flavors.”📖 Arctander |
Regulatory Status
| IOFI Classification | Nature Identical📖 Fenaroli |
Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.
Physicochemical Properties
DTXSID: DTXSID5057591
Physical Properties
| Molecular Weight | 114.144 g/mol🔬 EPA CompTox |
| Density | 0.918 g/cm^3🔬 EPA CTX |
| Boiling Point | 137.583 °C🔬 EPA CTX |
| Melting Point | -1.435 °C📊 OPERA |
| Flash Point | 2.142 °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 | 26.232 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.
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