3-Methyl-5-propyl-2-cyclohexen-1-one (CAS 3720-16-9) — Woody Middle Note Fragrance Ingredient
3-Methyl-5-propyl-2-cyclohexen-1-one
CAS 3720-16-9
What Is 3-Methyl-5-propyl-2-cyclohexen-1-one?
3-Methyl-5-propyl-2-cyclohexen-1-one is a synthetic fragrance ingredient used in perfumery to create woody, spicy, and slightly herbal nuances. It’s found in niche fragrances and some masculine colognes. This molecule adds complexity to woody accords, providing a dry, slightly peppery character that blends well with traditional masculine notes like sandalwood and vetiver.
Safety Profile
GENERALLY SAFEWhat Does 3-Methyl-5-propyl-2-cyclohexen-1-one Smell Like?
A dry, woody core with peppery spice highlights and subtle herbal undertones. Opens with a crisp, almost camphoraceous edge that quickly settles into a warm, slightly nutty heart. The dry-down reveals a persistent woody character reminiscent of aged cedar with a faint leathery nuance. Acts as a bridge between fresh top notes and deep base materials, adding dimensionality without overpowering.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used to enhance the flinty mineral character, adding dry woody complexity to the signature vetiver-iso E super accord.
Provides subtle peppery lift to the sandalwood base, contributing to the ‘pickle juice’ effect that makes this fragrance distinctive.
2D Molecular Structure
SMILES: CCCC1CC(C)=CC(=O)C1
Chemistry, Properties & Perfumer Guide
The Chemistry
A cyclic enone with a propyl substituent at the 5-position. Synthesized via alkylation of cyclohexenone precursors. The α,β-unsaturated ketone structure contributes to its dry woody character through conjugation effects. Lacks chiral centers but exhibits conformational flexibility that influences its odor profile.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | ~230 °C (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Woody accord modifier |
| Functional Fragrance | 0.1-0.5% | Up to 1% | Used sparingly for dry woody effects |
Classic Accords
Tip: Use to add dryness and diffusion to woody bases without adding sweetness.
Alternatives & Comparisons
More pronounced woody character with less spice, better for transparent wood accords.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions currently apply.
RIFM Assessment
Not currently evaluated by RIFM.
Sustainability
Synthetic production minimizes environmental impact compared to natural alternatives. Manufactured through efficient catalytic processes with good atom economy.
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References
- Bauer et al. (2001). Modern Synthetic Methods in Fragrance Chemistry. Chemistry & Biodiversity. DOI 10.1002/cbdv.200790032
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID80863256
Physical Properties
| Molecular Weight | 152.237 g/mol🔬 EPA CompTox |
| Density | 0.926 g/cm^3🔬 EPA CTX |
| Boiling Point | 249 °C🔬 EPA CTX |
| Melting Point | 20.931 °C📊 OPERA |
| Flash Point | 113 °C🔬 EPA CTX |
| Refractive Index | 1.46 Dimensionless📊 OPERA |
| Molar Volume | 168.308 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.65 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 2.676 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.676 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.18 Log10 unitless📊 OPERA |
| Water Solubility | 0.017 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.045 mmHg🔬 EPA CTX |
| Surface Tension | 30.714 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 | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 46.068 cm^3/mol📊 OPERA |
| Polarizability | 18.263 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.
