4-Methyl-3-penten-2-one (CAS 141-79-7) — Citrus Top Note Fragrance Ingredient
4-Methyl-3-penten-2-one
CAS 141-79-7
What Is 4-Methyl-3-penten-2-one?
4-Methyl-3-penten-2-one is a synthetic ketone used in fragrances to add fruity, woody, and slightly spicy nuances. It’s found in perfumes, air fresheners, and some cleaning products. This ingredient matters because it contributes to fresh, modern scent profiles, often enhancing citrus or green accords with its sharp yet pleasant character.
Safety Profile
GENERALLY SAFEWhat Does 4-Methyl-3-penten-2-one Smell Like?
4-Methyl-3-penten-2-one opens with a sharp, fruity burst reminiscent of unripe apples and green bananas. The heart reveals a woody undertone with hints of acetone-like sharpness, settling into a dry, slightly spicy base. Its evolution is linear but persistent, adding a crisp freshness that blends well with citrus and herbal notes.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to enhance the citrus-green accord, providing a crisp, invigorating top note that complements the herbal heart.
2D Molecular Structure
SMILES: CC(C)=CC(C)=O
Chemistry, Properties & Perfumer Guide
The Chemistry
4-Methyl-3-penten-2-one is a simple unsaturated ketone, part of the methylpentenone family. It is synthesized via aldol condensation of acetone or through oxidation of terpenes. Its structure allows for moderate volatility, making it useful in top notes. No chirality is present due to its symmetrical structure.
Physical & Chemical Properties
| Boiling Point | 130-132 °C |
|---|---|
| Density | 0.865 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Adds crispness to citrus accords |
| Functional Fragrance | 1-3% | Up to 8% | Enhances fresh cleaning product scents |
Classic Accords
Tip: Use sparingly to avoid overpowering other top notes.
Alternatives & Comparisons
A less sharp alternative with similar fruity-woody characteristics, used when milder effects are desired.
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 confirms safe use at current industry levels.
Sustainability
Synthesized from petrochemical precursors, this molecule has a moderate environmental footprint. Efforts to derive it from bio-based acetone could improve sustainability.
Explore 4-Methyl-3-penten-2-one
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References
- PubChem: 4-Methyl-3-penten-2-one PubChem CID
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID1029170
Physical Properties
| Molecular Weight | 98.145 g/mol🔬 EPA CompTox |
| Density | 0.858 g/cm^3🔬 EPA CTX |
| Boiling Point | 130.519 °C🔬 EPA CTX |
| Melting Point | -52.263 °C🔬 EPA CTX |
| Flash Point | 28.253 °C🔬 EPA CTX |
| Refractive Index | 1.418 Dimensionless📊 OPERA |
| Molar Volume | 118.112 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.7 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 1.212 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.212 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 3.36 Log10 unitless📊 OPERA |
| Water Solubility | 0.292 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 9.416 mmHg🔬 EPA CTX |
| Surface Tension | 23.238 dyn/cm📊 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 | 1 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 29.776 cm^3/mol📊 OPERA |
| Polarizability | 11.804 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.
