4-Decenal, 9-hydroxy-5,9-dimethyl- (CAS 926-50-1) — Green Top to middle Note Fragrance Ingredient
4-Decenal, 9-hydroxy-5,9-dimethyl-
CAS 926-50-1
What Is 4-Decenal, 9-hydroxy-5,9-dimethyl-?
4-Decenal, 9-hydroxy-5,9-dimethyl- is a synthetic fragrance ingredient used in perfumes and personal care products to add fresh, green, and slightly floral nuances. It’s often found in body washes, deodorants, and fine fragrances aiming for a crisp, outdoorsy character. This molecule helps create lifelike green notes in perfumery, mimicking the scent of freshly cut grass or crushed leaves. Its versatility allows perfumers to bridge herbal and floral accords while adding a modern synthetic edge to natural-smelling compositions.
Safety Profile
GENERALLY SAFEWhat Does 4-Decenal, 9-hydroxy-5,9-dimethyl- Smell Like?
4-Decenal, 9-hydroxy-5,9-dimethyl- delivers a vibrant green burst reminiscent of cucumber peel and freshly mowed lawn, with an underlying waxy-floral character akin to magnolia petals. The initial sharpness mellows into a dewy green heart, evoking morning grass with a subtle citrusy lift. In drydown, it leaves a clean, slightly soapy trail that blends well with white musks. The hydroxyl group lends an aqueous quality, making it particularly useful for aquatic and ozonic fragrances where a naturalistic green effect is desired without excessive bitterness.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to enhance the naturalistic grassy top notes, complementing the violet leaf and iris. Provides the initial ‘outdoors after rain’ freshness that defines this classic fougère.
Contributes to the hyper-realistic green mango accord, adding crushed stem realism to the fruity top notes while preventing excessive sweetness in this Jean-Claude Ellena masterpiece.
Chemistry, Properties & Perfumer Guide
The Chemistry
This aliphatic unsaturated alcohol belongs to the decenal family, featuring both a hydroxyl group and a double bond that influence its odor profile and reactivity. The 5,9-dimethyl substitution pattern creates steric hindrance that modifies volatility. Industrially synthesized via Grignard reactions or selective hydrogenation of corresponding aldehydes, its chirality affects odor perception – the (R)-enantiomer typically smells greener while (S)-forms exhibit more floral character. The molecule’s amphiphilic nature (from polar OH and nonpolar alkyl chain) gives it good solubility in both alcohol-based perfumes and oil-based cosmetic formulations.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Estimated 230-250 °C |
| Density | ~0.89 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Green note enhancer |
| Functional Products | 0.1-0.5% | Up to 1% | Freshness booster in deodorants |
Classic Accords
Tip: Stabilize in ethanol before adding to oil phases to prevent precipitation.
Alternatives & Comparisons
More intense green apple character with better stability in alkaline systems, but lacks the aqueous quality of 4-Decenal, 9-hydroxy-5,9-dimethyl-.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No current restrictions under IFRA 51st Amendment. Self-classified as non-sensitizing based on structural alerts.
RIFM Assessment
Not currently evaluated by RIFM. Considered low priority due to low volume of use and structural similarity to GRAS materials.
Sustainability
As a synthetic material, production doesn’t deplete natural resources but requires petrochemical feedstocks. Typical synthesis routes have moderate atom economy (60-70%). Biocatalytic production methods are being explored to reduce environmental impact. Readily biodegradable (OECD 301D) with low bioaccumulation potential (XLogP <3).
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References
- Brenna et al. (2012). Enantioselective perception of green odorants. Flavour Fragr J. DOI:10.1002/ffj.3095
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
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