2-Pentenal (CAS 764-39-6) — Green Top Note Fragrance Ingredient
2-Pentenal
CAS 764-39-6
What Is 2-Pentenal?
2-Pentenal is a synthetic organic compound often used in fragrances to add green, leafy, or fruity nuances. It’s found in trace amounts in some natural sources like fruits and vegetables. This ingredient matters because it helps create realistic ‘outdoorsy’ or ‘just-cut’ impressions in perfumes, bridging the gap between citrus top notes and floral heart notes.
Safety Profile
GENERALLY SAFEWhat Does 2-Pentenal Smell Like?
2-Pentenal delivers a sharp, green-aldehyde burst reminiscent of freshly crushed leaves or unripe apples. The initial piercing quality mellows into a waxy, slightly fatty undertone akin to cucumber skin. In drydown, it leaves a faint trace of bitter almond-like nuance, making it useful for creating ‘stemmy’ floral effects or enhancing citrus top notes with verdant realism.
2D Molecular Structure
SMILES: CCC=CC=O
Chemistry, Properties & Perfumer Guide
The Chemistry
2-Pentenal is an α,β-unsaturated aldehyde with the molecular formula C5H8O. This small molecule belongs to the same chemical family as acrolein but with less reactivity. Industrially produced via oxidation of pentenes or as a byproduct in hydrocarbon cracking. The (E)-isomer predominates in fragrance applications due to greater stability.
Physical & Chemical Properties
| Boiling Point | 120-122 °C |
|---|---|
| Density | 0.855 g/cm³ |
| Refractive Index | 1.428 |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Functional Fragrances | 0.1-0.5% | Up to 1% | For green freshness |
| Fine Fragrance | 0.01-0.1% | Up to 0.3% | Supporting note |
Classic Accords
Tip: Use at trace levels to lift citrus top notes without overwhelming.
Alternatives & Comparisons
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions currently apply.
GHS Classification
RIFM Assessment
RIFM assessment completed – safe at current use levels.
Sustainability
Synthesized from petrochemical feedstocks but used in such small quantities that environmental impact is minimal. No known natural sustainable sources available at commercial scale.
Explore 2-Pentenal
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References
- PubChem Compound Summary for CID 5283348 PubChem
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 764-39-6Physical Properties
| Molecular Weight | 84.12 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1🔬 PubChem |
| Boiling Point | 118 °C🔬 EPA CompTox |
| Vapor Pressure | 64.5654 mmHg @ 25°C📊 OPERA |
| Flash Point | 22.8 °C🔬 EPA CompTox |
| Involatility Index | 7.5872💻 Calculated |
| log Kp (skin permeability) | -2.503💻 Calculated |
| SMILES | CCC=CC=O🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Very fast💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Functional Groups | aldehydealkene💻 RDKit |
| “Extremely diffusive, “gassy “-sweet odor, in ulpha-Methyl acrolein. only in extreme dilution fairly pleasant her- NOTE: Do not confuse this with: baceous-balsamic and remotely Orange-like.”📖 Arctander | |
| 2-Pentenal has a pungent, green, apple, orange, tomato odor.📖 Fenaroli | |
Sensory Thresholds
| Odor Detection Threshold | 4.3252 ppm (n=5)📖 van Gemert |
Regulatory Status
| IOFI Classification | Nature Identical📖 Fenaroli |
Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.
Physicochemical Properties
DTXSID: DTXSID9061091
Physical Properties
| Molecular Weight | 84.118 g/mol🔬 EPA CompTox |
| Density | 0.853 g/cm^3🔬 EPA CTX |
| Boiling Point | 118.543 °C📊 OPERA |
| Melting Point | -52.648 °C📊 OPERA |
| Flash Point | 23.215 °C📊 OPERA |
| Refractive Index | 1.413 Dimensionless📊 OPERA |
| Molar Volume | 102.002 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 0.879 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 0.879 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 0.879 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.27 Log10 unitless📊 OPERA |
| Water Solubility | 0.325 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 42.753 mmHg📊 OPERA |
| Viscosity | 0.426 cP📊 OPERA |
| Surface Tension | 24.118 dyn/cm📊 OPERA |
| Thermal Conductivity | 148.484 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 | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 25.458 cm^3/mol📊 OPERA |
| Polarizability | 10.092 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.
