2-trans-Dodecenal (CAS 20407-84-5) — Citrus Top Note Fragrance Ingredient
2-trans-Dodecenal
CAS 20407-84-5
What Is 2-trans-Dodecenal?
2-trans-Dodecenal is a synthetic fragrance ingredient that adds a waxy, citrusy, and slightly metallic character to perfumes. Consumers might encounter it in citrus-forward fragrances or functional products like detergents where a bright, clean note is desired. This aldehyde is particularly valued for its ability to enhance the realism of citrus top notes while adding a subtle complexity that prevents compositions from smelling too one-dimensional.
Safety Profile
USE WITH AWARENESSWhat Does 2-trans-Dodecenal Smell Like?
2-trans-Dodecenal opens with a burst of waxy citrus peel – imagine the bright zest of a freshly peeled tangerine with a metallic edge like the tang of blood orange. As it evolves, the scent reveals a soapy-clean aldehydic quality reminiscent of high-end laundry detergents, underpinned by a faint fatty note like candle wax. The dry-down leaves a subtle, lingering impression of citrus rind and warm paraffin, making it particularly useful for creating realistic citrus accords that don’t fade too quickly.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to amplify the sparkling citrus opening, adding a polished, slightly waxy dimension to the bergamot and lemon notes that makes them more tenacious on skin.
Contributes to the crisp, aquatic citrus character that defines this summer staple, blending with Sicilian lemon to create a more dimensional top note.
Chemistry, Properties & Perfumer Guide
The Chemistry
2-trans-Dodecenal is an α,β-unsaturated aldehyde with a 12-carbon chain. As a trans-configured alkene, it has greater stability and different olfactory characteristics compared to its cis counterpart. Industrially produced via hydroformylation of 1-undecene followed by dehydrogenation, this molecule exemplifies how controlled synthetic processes can create consistent fragrance materials that outperform natural extracts in stability and performance.
Physical & Chemical Properties
| Boiling Point | 237-239 °C |
|---|---|
| Density | 0.84 g/cm³ |
| Vapor Pressure | 0.008 mmHg at 25°C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Used to boost citrus freshness |
| Functional Fragrances | 0.05-0.2% | Up to 0.5% | Adds clean character to detergents |
| Cosmetics | 0.01-0.1% | Up to 0.3% | Provides subtle citrus enhancement |
Classic Accords
Tip: Use at trace levels with citrus oils to extend their diffusion without overwhelming the blend.
Alternatives & Comparisons
For a less metallic, more straightforward citrus-waxy character with better stability in alkaline systems.
When a more floral, violet leaf-like aldehydic note is desired instead of the citrus-waxy profile.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions under Amendment 51. Self-imposed limits recommended due to sensitization potential.
GHS Classification
RIFM Assessment
RIFM evaluation confirms safe use at current industry levels with recommended concentration limits.
Sustainability
As a synthetic material, 2-trans-Dodecenal offers consistent quality without natural sourcing constraints. Production from petrochemical feedstocks raises carbon footprint concerns, but its high potency means minimal quantities are needed. Future green chemistry routes may utilize bio-based 1-undecene from castor oil derivatives.
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References
- Bauer et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH. ISBN 978-3-527-30364-6
- IFRA Standards Library IFRA Amendment 51
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
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