Methylcyclopentenolone (CAS 80-71-7) — Sweet Heart Note Fragrance Ingredient
Methylcyclopentenolone
CAS 80-71-7
What Is Methylcyclopentenolone?
Methylcyclopentenolone is a synthetic fragrance ingredient prized for its warm, caramel-like aroma with woody undertones. You’ll encounter it in gourmand perfumes, flavored tobaccos, and some vanilla-scented candles. This molecule matters because it adds depth to sweet compositions without being cloying. Its subtle nutty character helps bridge fruity top notes with deeper base accords.
Safety Profile
GENERALLY SAFEWhat Does Methylcyclopentenolone Smell Like?
Methylcyclopentenolone unfolds like burnt sugar dissolving into aged whiskey – initially sharp caramelization giving way to rounded maple syrup richness. The top has a fleeting metallic edge that quickly softens into toasted hazelnuts dusted with cocoa powder. As it dries down, the sweetness becomes more refined, revealing faint tobacco leaf nuances and a whisper of sandalwood. Unlike simpler sweeteners, it maintains dimensional complexity for hours, never collapsing into flat saccharine monotony but instead evolving toward a sophisticated gourmand-woody hybrid.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Provides the caramelized sugar backbone that makes Angel’s gourmand pyramid revolutionary. Blends with ethyl maltol to create its signature cotton candy effect while adding woody sophistication.
Used sparingly to bridge the dried fruit accord with the vanilla-tobacco base, adding a molasses-like depth that prevents the composition from becoming too literal.
Contributes to the rum-soaked almond illusion in this dark gourmand, where its nutty facets enhance the coffee-chocolate accord without overwhelming the composition.
Works synergistically with patchouli to create the fragrance’s famous chocolate-patchouli effect, its caramelized character rounding out the rough edges of the earthy base.
Provides the subtle praline nuance that distinguishes this sweet floral from simpler gourmands, adding sophistication to the vanilla-iris heart.
2D Molecular Structure
SMILES: CC1=C(O)C(=O)CC1
Chemistry, Properties & Perfumer Guide
The Chemistry
Methylcyclopentenolone belongs to the cyclotene class of compounds, characterized by a cyclopentenone core with methyl substitution. While structurally related to naturally occurring maple lactone, commercial material is exclusively synthetic. Industrial production typically involves condensation reactions of diacetyl with formaldehyde derivatives, followed by controlled oxidation. The molecule’s stereochemistry isn’t fixed, with racemic mixtures being most common in fragrance applications. Its relatively low molecular weight contributes to moderate volatility, while the ketone functionality provides hydrogen bonding sites that influence both solubility and odor persistence.
Physical & Chemical Properties
| Appearance | White crystalline powder |
|---|---|
| Melting Point | 92-94 °C |
| Solubility | Soluble in ethanol, propylene glycol |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 3% | Gourmand modifier |
| Candles | 1-3% | Up to 5% | Vanilla enhancer |
| Flavored Tobacco | 0.1-0.5% | Up to 1% | Caramel note |
| Bath Products | 0.2-1% | Up to 1.5% | Warmth booster |
Classic Accords
Tip: Use below 3% to avoid overwhelming other notes – its sweetness amplifies exponentially with concentration.
Alternatives & Comparisons
For simpler cotton candy effects, though lacks methylcyclopentenolone’s woody sophistication.
When a more literal maple syrup character is desired, though less versatile in blending.
For strawberry-jam sweetness in fruity compositions rather than caramelized depth.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions – unrestricted use under current standards (Amendment 49).
RIFM Assessment
RIFM assessment confirms safe use at current industry levels with wide margins of safety.
Sustainability
As a purely synthetic material, methylcyclopentenolone production avoids agricultural land use. Modern synthesis routes have reduced solvent waste through catalytic processes. Its potency means relatively small quantities are needed compared to natural extracts, reducing overall environmental impact per kilogram of finished product. No known ecological toxicity concerns at usage levels.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781439832274
- Sell, C. (2006). The Chemistry of Fragrances. RSC Publishing. ISBN 9780854048243
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID4035128
Physical Properties
| Molecular Weight | 112.128 g/mol🔬 EPA CompTox |
| Density | 1.151 g/cm^3🔬 EPA CTX |
| Boiling Point | 242 °C🔬 EPA CTX |
| Melting Point | 100.156 °C🔬 EPA CTX |
| Flash Point | 100.8 °C🔬 EPA CTX |
| Refractive Index | 1.463 Dimensionless📊 OPERA |
| Molar Volume | 101.703 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 0.4 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 0.037 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 0.037 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.95 Log10 unitless📊 OPERA |
| Water Solubility | 0.491 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 1.575 mmHg🔬 EPA CTX |
| Surface Tension | 35.919 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 37.3 Ų💻 Computed |
| H-Bond Donors | 1 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 28.028 cm^3/mol📊 OPERA |
| Polarizability | 11.111 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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