9-Decenal (CAS 39770-05-03) — Citrus Top Note Fragrance Ingredient
9-Decenal
CAS 39770-05-03
What Is 9-Decenal?
9-Decenal is a synthetic fragrance ingredient that creates fresh, citrusy, and slightly floral scents. You’ll find it in modern perfumes, especially those aiming for a crisp, clean character. This molecule matters because it adds a unique sparkling quality to fragrances, helping create the illusion of freshly peeled citrus fruits without using actual citrus oils that can fade quickly.
Safety Profile
GENERALLY SAFEWhat Does 9-Decenal Smell Like?
9-Decenal bursts with a vibrant, aldehydic citrus character reminiscent of freshly peeled mandarin rind, evolving into a crisp green melon-like freshness. The initial sharpness softens into a delicate floralcy akin to neroli blossoms floating on a breeze. Unlike heavier citrus oils, it maintains remarkable tenacity for an aldehyde, leaving a clean, slightly waxy impression in the dry-down that suggests sun-warmed citrus leaves rather than fruit pulp.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the citrus top notes while adding durability, creating the illusion of freshly squeezed Sicilian lemons that persist longer than natural citrus oils would allow.
Provides the sparkling ambergris effect in the opening, mimicking sea spray with its aldehyde freshness before blending into the woody-amber heart.
Chemistry, Properties & Perfumer Guide
The Chemistry
9-Decenal is a straight-chain aliphatic aldehyde with ten carbon atoms. As a synthetic molecule, it’s produced through hydroformylation of 1-nonene or oxidation of 9-decenol. The aldehyde functional group at position 9 creates its distinctive odor profile. Unlike many citrus-smelling compounds, its relatively long carbon chain provides better stability against oxidation while maintaining volatility appropriate for top notes.
Physical & Chemical Properties
| Boiling Point | ~210 °C (estimated) |
|---|---|
| Density | ~0.84 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Adds sparkling citrus lift |
| Functional Fragrance | 0.1-0.5% | Up to 1% | Clean laundry applications |
Classic Accords
Tip: Use to extend citrus top notes without the phototoxicity concerns of natural citrus oils.
Alternatives & Comparisons
When a less citrusy, more waxy-orange character is desired. Has greater tenacity but lacks the green freshness of 9-decenal.
For stronger lemon character, though more prone to oxidation and skin sensitivity concerns.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No restrictions under IFRA 51st Amendment. Classified as safe for use in all fragrance categories.
RIFM Assessment
Evaluated by RIFM in 2018 with no significant safety concerns at standard usage levels.
Sustainability
As a synthetic material, 9-decenal avoids agricultural land use associated with natural citrus oils. Production typically uses petrochemical feedstocks, though bio-based routes from renewable sources are being developed. Its efficiency means less material is needed compared to natural citrus oils to achieve similar effects.
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References
- Bauer et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH.
- IFRA Standards Library IFRA 51st Amendment
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
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