3-Ethyl-2-hydroxy-2-cyclopenten-1-one (CAS 21835-01-08) — Sweet Heart to base Note Fragrance Ingredient
3-Ethyl-2-hydroxy-2-cyclopenten-1-one
CAS 21835-01-08
What Is 3-Ethyl-2-hydroxy-2-cyclopenten-1-one?
3-Ethyl-2-hydroxy-2-cyclopenten-1-one is a synthetic fragrance compound used to add caramel-like, sweet woody nuances to perfumes. You’ll encounter it in gourmand and oriental fragrances where it contributes warm depth. This ingredient matters because it helps create rich, comforting scent profiles without using natural extracts, making fragrances more sustainable and consistent.
Safety Profile
GENERALLY SAFEWhat Does 3-Ethyl-2-hydroxy-2-cyclopenten-1-one Smell Like?
This molecule delivers a fascinating duality – opening with an almost burnt sugar caramel sharpness that quickly softens into velvety wood tones. Imagine the crisp edge of crème brûlée meeting the smokiness of aged bourbon barrels. As it dries down, it reveals a subtle leathery undertone, like well-worn bookbinding. The evolution is surprisingly long-lasting for a synthetic, with the sweet facets persisting while the woody base becomes more pronounced over hours.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to enhance the vanilla-caramel accord while adding woody depth that bridges the tobacco leaf and dried fruit notes.
Contributes to the innovative ‘foody’ accord, providing caramelized sugar effects without actual gourmand ingredients.
Chemistry, Properties & Perfumer Guide
The Chemistry
3-Ethyl-2-hydroxy-2-cyclopenten-1-one belongs to the cyclopentenolone class, structurally related to furaneol. It’s produced through aldol condensation of ethyl cyclopentanone derivatives followed by oxidation. The molecule’s stereochemistry is particularly interesting – the hydroxyl group at position 2 creates a chiral center that influences its odor profile. Industrial synthesis typically yields a racemic mixture, though enantioselective routes exist for fine fragrance applications.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Estimated 230-240°C |
| Density | ~1.05 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Used as modifier rather than main note |
| Candles | 1-3% | Up to 8% | Adds warm diffusion |
Classic Accords
Tip: Use with ionones to create sophisticated tobacco effects without actual tobacco absolute.
Alternatives & Comparisons
More intensely caramel-like but lacks the woody depth. Better for true gourmand applications.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted under any IFRA standards (as of 48th Amendment).
RIFM Assessment
RIFM has reviewed this material and found no significant safety concerns at typical usage levels.
Sustainability
As a synthetic material, this compound avoids agricultural land use and seasonal variability. Production typically uses green chemistry principles with high atom economy. No endangered species or deforestation concerns associated with its manufacture.
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References
- Brenna et al. (2002). Odor-active compounds in tobacco. Flavour and Fragrance Journal. DOI:10.1002/ffj.1089
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
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