Decenal Isomers (CAS 174155-47-6) — Green Top to middle Note Fragrance Ingredient
Decenal Isomers
CAS 174155-47-6
What Is Decenal Isomers?
Decenal isomers are synthetic fragrance ingredients that mimic the fresh, citrusy-green scent of natural aldehydes. They’re commonly found in modern perfumes, especially those aiming for a crisp, clean character. These molecules matter because they offer perfumers precise control over green, slightly waxy citrus effects without the instability of some natural counterparts.
Safety Profile
USE WITH AWARENESSWhat Does Decenal Isomers Smell Like?
Decenal isomers burst with a vibrant, green-citrus intensity reminiscent of freshly crushed lime leaves and unripe mandarin peel. The opening is effervescent – like sparkling aldehydes wrapped in a waxy cucumber skin. As it evolves, a cleaner, almost metallic greenness emerges, recalling the crisp bite of galbanum but with a smoother transition. The dry-down reveals a subtle, mossy undertone that anchors the brightness without turning woody. Unlike simpler aldehydes, these isomers maintain remarkable tenacity while avoiding soapy overtones.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the citrus top notes while adding an innovative green freshness that bridges to the floral heart. The isomers’ waxy quality helps blend the sharp bergamot with rounder magnolia.
Jean-Claude Ellena employs decenal isomers to create the illusion of crushed green mango skin – their slightly bitter, vegetal aspect perfectly complements the tropical fruit accord.
2D Molecular Structure
SMILES: C\C=C\CCCCCCC=O
Chemistry, Properties & Perfumer Guide
The Chemistry
Decenal isomers belong to the C10 aldehyde family, specifically unsaturated decenals with varying double bond positions. While naturally occurring in trace amounts in citrus peels and some leafy greens, commercial versions are synthesized via controlled oxidation of corresponding alcohols or through olefin metathesis. The exact isomeric mixture affects the odor profile significantly – trans-2-decenal is sharper and more citrus-like, while trans-4-decenal leans greener and more vegetative. Unlike saturated aldehydes, these unsaturated variants resist turning soapy at higher concentrations, making them valuable for modern green accords.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Approx. 210-230 °C (mixture) |
| Flash Point | >100 °C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | For fresh top notes |
| Functional Fragrances | 0.05-0.2% | Up to 0.3% | Green-citrus cleaners |
| Cosmetics | 0.01-0.1% | Up to 0.15% | Limited by potential sensitization |
Classic Accords
Tip: Stabilize in ethanol before adding to water-based systems to prevent aldehyde polymerization.
Alternatives & Comparisons
For more cucumber-like effects with less citrus. Higher impact at lower concentrations but more prone to oxidation.
When a smoother, less aggressive green note is needed. Retains some waxy character but with better floral compatibility.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No specific restrictions under IFRA 49th Amendment. General aldehyde precautions apply.
EU Allergen Declaration
Not listed in EU allergen regulations
GHS Classification
RIFM Assessment
RIFM evaluation ongoing for specific isomeric mixtures. Preliminary data suggests safe use at current industry levels.
Sustainability
As synthetic materials, decenal isomers avoid agricultural land use but require petrochemical feedstocks. Modern production methods employ catalytic processes with reduced solvent waste. Their high potency means minimal quantities are needed per formulation, reducing overall environmental load compared to some natural extracts.
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References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090869
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID60889015
Physical Properties
| Molecular Weight | 154.253 g/mol🔬 EPA CompTox |
| Density | 0.849 g/cm^3📊 OPERA |
| Boiling Point | 215.476 °C📊 OPERA |
| Melting Point | 0.138 °C📊 OPERA |
| Flash Point | 86.161 °C📊 OPERA |
| Refractive Index | 1.44 Dimensionless📊 OPERA |
| Molar Volume | 184.536 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.47 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.47 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.47 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.06 Log10 unitless📊 OPERA |
| Water Solubility | 0.002 mol/L📊 OPERA |
| Henry's Law Constant | 0.001 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.133 mmHg📊 OPERA |
| Viscosity | 1.669 cP📊 OPERA |
| Surface Tension | 28.424 dyn/cm📊 OPERA |
| Thermal Conductivity | 143.394 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 17.07 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 7 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 48.622 cm^3/mol📊 OPERA |
| Polarizability | 19.275 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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