2-Undecenal (CAS 2463-77-6) — Citrus Top Note Fragrance Ingredient
2-Undecenal
CAS 2463-77-6
What Is 2-Undecenal?
2-Undecenal is a synthetic aldehyde used in perfumery for its intense waxy, citrusy, and slightly metallic odor. Commonly found in household cleaners and air fresheners for its powerful scent. This ingredient matters because it provides long-lasting freshness and enhances citrus notes in fragrances, though its potency requires careful dosing.
Safety Profile
USE WITH AWARENESSWhat Does 2-Undecenal Smell Like?
2-Undecenal bursts with a sharp, waxy citrus note reminiscent of lemon peel and candle wax. The initial intensity mellows into a cleaner, soapy undertone with a faint metallic edge. Over time, it evolves into a soft, slightly fatty aroma, akin to crushed green leaves mixed with a whisper of fresh laundry.
2D Molecular Structure
SMILES: CCCCCCCCC=CC=O
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Undecenal is an unsaturated aldehyde with an 11-carbon chain. It belongs to the class of α,β-unsaturated aldehydes, known for their reactivity and strong odors. Typically synthesized via hydroformylation of decene or oxidation of undecenol. Its structure makes it prone to polymerization and oxidation, requiring stabilization in formulations.
Physical & Chemical Properties
| Boiling Point | Not well documented |
|---|---|
| Density | Not well documented |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Used sparingly for citrus lift |
| Functional Fragrance | 0.5-2% | Up to 3% | Adds freshness to cleaners |
Classic Accords
Tip: Use in trace amounts to avoid overwhelming the composition.
Alternatives & Comparisons
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions currently apply.
EU Allergen Declaration
Not listed as an EU allergen.
GHS Classification
RIFM Assessment
RIFM assessment pending; limited data available.
Sustainability
Synthetic production avoids agricultural impacts but relies on petrochemical feedstocks. Energy-intensive processes involved in synthesis.
Explore 2-Undecenal
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References
- PubChem: 2-Undecenal CID 2463-77-6
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID701377558
Physical Properties
| Molecular Weight | 168.28 g/mol🔬 EPA CompTox |
| Density | 0.842 g/cm^3🔬 EPA CTX |
| Boiling Point | 229.355 °C📊 OPERA |
| Melting Point | 2.434 °C📊 OPERA |
| Flash Point | 103.852 °C📊 OPERA |
| Refractive Index | 1.443 Dimensionless📊 OPERA |
| Molar Volume | 201.043 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 4.176 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 4.176 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 4.176 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.83 Log10 unitless📊 OPERA |
| Water Solubility | 0.001 mol/L📊 OPERA |
| Henry's Law Constant | 0.001 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.049 mmHg📊 OPERA |
| Viscosity | 1.915 cP📊 OPERA |
| Surface Tension | 28.835 dyn/cm📊 OPERA |
| Thermal Conductivity | 145.497 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 | 8 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 53.255 cm^3/mol📊 OPERA |
| Polarizability | 21.112 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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