Methyl cyclopentylideneacetate (CAS 40203-73-4) — Green Top to Mid Note Fragrance Ingredient
Methyl cyclopentylideneacetate
CAS 40203-73-4
What Is Methyl cyclopentylideneacetate?
Methyl cyclopentylideneacetate is a synthetic fragrance ingredient used in modern perfumery to create fresh, fruity-green accents. You’ll encounter it in body sprays, fabric softeners, and some citrusy colognes. This versatile molecule helps perfumers achieve a crisp, natural effect without relying on botanicals. Its stability and cost-effectiveness make it popular in mass-market fragrances where consistent performance matters.
Safety Profile
GENERALLY SAFEWhat Does Methyl cyclopentylideneacetate Smell Like?
Methyl cyclopentylideneacetate bursts with a zesty, green-apple freshness that gradually reveals subtle floral undertones. Imagine biting into a just-ripe pear while standing in a sunlit orchard – that initial crispness dominates the top notes. As it evolves, the heart develops a delicate rosy character, like petals brushed with morning dew. The dry-down is remarkably clean, leaving a faint musky-woody whisper that prevents the composition from feeling overly sweet. This ingredient performs exceptionally well in aquatic and fruity-floral fragrances, where it adds lift and naturalism without overpowering delicate accords.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as a crisp top note modifier that enhances the citrusy opening while adding depth to the apple accord, creating that signature Mediterranean freshness.
Provides subtle green-floral facets that bridge the violet leaf and musk notes, contributing to the fragrance’s transparent yet persistent character.
2D Molecular Structure
SMILES: COC(=O)C=C1CCCC1
Chemistry, Properties & Perfumer Guide
The Chemistry
Methyl cyclopentylideneacetate belongs to the ester class of fragrance compounds, specifically a cyclopentene derivative with an acrylate ester functional group. Industrially synthesized through acid-catalyzed condensation reactions, this molecule features a strained cyclopentene ring that contributes to its vibrant olfactory profile. The α,β-unsaturated ester moiety makes it moderately reactive, requiring stabilization in finished products. While not found in nature, its structure mimics certain volatile organic compounds emitted by ripening fruits, explaining its convincing naturalistic effect in perfumery.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Approx. 210-215 °C (estimated) |
| Density | ~1.05 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Used as a fresh green modifier |
| Functional Fragrances | 0.1-0.5% | Up to 1% | Adds crispness to laundry products |
Classic Accords
Tip: Stabilize with antioxidants when blending with citrus top notes to prevent premature oxidation.
Alternatives & Comparisons
For a more straightforward fruity note without the green complexity, though lacks the floral depth of methyl cyclopentylideneacetate.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No current IFRA restrictions (as of 51st Amendment).
RIFM Assessment
Under review by RIFM, preliminary data suggests low sensitization potential.
Sustainability
As a synthetic material, methyl cyclopentylideneacetate offers consistent quality without agricultural variability. Its production typically involves petrochemical feedstocks, though newer bio-based synthesis routes are being explored. The material’s efficiency at low concentrations reduces environmental load compared to some natural alternatives requiring higher usage levels.
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References
- Bauer et al. (2001). Modern Synthetic Methods in Perfumery. Chemistry & Biodiversity. DOI:10.1002/cbdv.200790032
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 40203-73-4Physical Properties
| Molecular Weight | 140.18 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.6🔬 PubChem |
| Boiling Point | 199 °C🔬 EPA CompTox |
| Vapor Pressure | 0.2625 mmHg @ 25°C📊 OPERA |
| Flash Point | 74 °C🔬 EPA CompTox |
| Involatility Index | 0.0239💻 Calculated |
| log Kp (skin permeability) | -2.419💻 Calculated |
| SMILES | COC(=O)C=C1CCCC1🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Slow💻 Calculated |
| Persistence Score | 0.8 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | citrusgreen• leffingwell |
| Functional Groups | esteretheralkene💻 RDKit |
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: DTXSID2052077
Physical Properties
| Molecular Weight | 140.182 g/mol🔬 EPA CompTox |
| Density | 1.01 g/cm^3🔬 EPA CTX |
| Boiling Point | 199 °C🔬 EPA CTX |
| Melting Point | -56 °C🔬 EPA CTX |
| Flash Point | 74 °C🔬 EPA CTX |
| Refractive Index | 1.554 Dimensionless📊 OPERA |
| Molar Volume | 125.916 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.063 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 2.063 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.063 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.43 Log10 unitless📊 OPERA |
| Water Solubility | 0.011 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.352 mmHg🔬 EPA CTX |
| Surface Tension | 39.829 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 | 1 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 40.348 cm^3/mol📊 OPERA |
| Polarizability | 15.995 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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