4-Pentenoic acid, 2-acetyl-4-methyl-, ethyl ester (CAS 20962-70-3) — Green Top to middle Note Fragrance Ingredient
4-Pentenoic acid, 2-acetyl-4-methyl-, ethyl ester
CAS 20962-70-3
What Is 4-Pentenoic acid, 2-acetyl-4-methyl-, ethyl ester?
This synthetic fragrance ingredient is a specialized chemical compound used in modern perfumery to create unique fruity-green accords. You’ll encounter it in niche fragrances where perfumers push creative boundaries. Though not widely known, it matters because it offers a crisp, diffusive quality that can’t be easily replicated with natural materials alone.
Safety Profile
USE WITH AWARENESSWhat Does 4-Pentenoic acid, 2-acetyl-4-methyl-, ethyl ester Smell Like?
A vibrant burst of green apple peel and unripe pear dominates the opening, with a sharp, almost metallic edge that recalls freshly cut stems. As it evolves, a subtle lactonic undertone emerges like yogurt-covered green grapes, while maintaining an energetic, diffusive quality. The dry-down reveals a clean, woody-musky base reminiscent of wet tree bark after rain, with lingering fruity facets that dance at the periphery of perception.
2D Molecular Structure
SMILES: CCOC(=O)C(CC(C)=C)C(C)=O
Chemistry, Properties & Perfumer Guide
The Chemistry
This ester belongs to the class of unsaturated fatty acid derivatives with acetyl substitution. Synthesized through esterification reactions between the corresponding acid and ethanol, its structure features both α,β-unsaturation and acetyl functionality that contribute to its reactive nature. The methyl group at the 4-position creates steric hindrance that influences both volatility and odor characteristics.
Physical & Chemical Properties
| Boiling Point | Not established |
|---|---|
| Density | Not established |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Used as a modifier in fruity-green accords |
| Functional Fragrance | 0.05-0.2% | Up to 0.5% | For fresh, clean effects |
Classic Accords
Tip: Use sparingly in citrus bases to add dimensionality without overpowering.
Alternatives & Comparisons
Similar green-fruity character but less sharp, with better stability in alkaline formulations.
More conventional fruity-green note with established safety profile for mass-market products.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No specific IFRA restrictions currently apply to this material.
RIFM Assessment
Not currently evaluated by RIFM. Recommended for evaluation before widespread use.
Sustainability
As a synthetic material, production involves petrochemical feedstocks but requires relatively simple synthesis with moderate energy input. No known ecological concerns regarding biodegradation, though full environmental impact studies are lacking. Offers an alternative to harvesting rare natural materials.
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Physicochemical Properties
DTXSID: DTXSID1051482
Physical Properties
| Molecular Weight | 184.235 g/mol🔬 EPA CompTox |
| Density | 0.967 g/cm^3📊 OPERA |
| Boiling Point | 224.947 °C📊 OPERA |
| Melting Point | -19.008 °C📊 OPERA |
| Flash Point | 86.3 °C📊 OPERA |
| Refractive Index | 1.438 Dimensionless📊 OPERA |
| Molar Volume | 189.476 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.998 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 1.998 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.998 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.55 Log10 unitless📊 OPERA |
| Water Solubility | 0.034 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.125 mmHg📊 OPERA |
| Viscosity | 1.449 cP📊 OPERA |
| Surface Tension | 30.1 dyn/cm📊 OPERA |
| Thermal Conductivity | 134.611 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 43.37 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 3 count💻 Computed |
| Rotatable Bonds | 5 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 49.709 cm^3/mol📊 OPERA |
| Polarizability | 19.706 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.
