1-Ethynylcyclohexyl acetate (CAS 5240-32-4) — Green Top to middle Note Fragrance Ingredient
1-Ethynylcyclohexyl acetate
CAS 5240-32-4
What Is 1-Ethynylcyclohexyl acetate?
1-Ethynylcyclohexyl acetate is a synthetic fragrance ingredient used in modern perfumery to create fresh, green, and slightly woody accords. You’ll encounter it in contemporary citrus and floral fragrances. This molecule matters because it adds a crisp, modern edge to compositions, bridging natural and synthetic elements with its unique character.
Safety Profile
GENERALLY SAFEWhat Does 1-Ethynylcyclohexyl acetate Smell Like?
1-Ethynylcyclohexyl acetate opens with a sharp, green freshness reminiscent of crushed stems and citrus peel, with a metallic edge like rain on hot pavement. As it evolves, a smooth woody-herbal heart emerges, suggesting damp cedarwood and fresh sage. The dry-down reveals a clean, slightly musky base with echoes of ozone and mineral notes. The overall effect is modern and angular – like polished stainless steel contrasted with living greenery.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here to create the ‘metallic ozone’ accord, contributing to the futuristic spacewalk concept with its sharp green-woody character.
Provides the crisp synthetic greenery that contrasts with natural galbanum, creating tension between organic and laboratory-grown elements.
2D Molecular Structure
SMILES: CC(=O)OC1(CCCCC1)C#C
Chemistry, Properties & Perfumer Guide
The Chemistry
1-Ethynylcyclohexyl acetate is an acetylated cyclohexyl derivative with terminal alkyne functionality. The molecule combines a rigid cyclohexane ring with reactive ethynyl and acetate groups, creating unique odor properties. Industrial synthesis typically involves acetylating 1-ethynylcyclohexanol. The triple bond contributes to its sharp top notes while the cyclohexyl structure provides woody depth.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | Estimated 200-220°C |
| Density | Approx. 0.95 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Modern fresh-woody accords |
| Functional Fragrance | 0.1-0.5% | Up to 1% | Clean green notes |
Classic Accords
Tip: Use sparingly in citrus compositions to add structural definition without overwhelming freshness.
Alternatives & Comparisons
Offers similar green-woody character but with more pronounced herbal notes and better stability in alkaline systems.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions currently apply to this material.
RIFM Assessment
Not currently evaluated by RIFM – considered low exposure risk due to limited usage.
Sustainability
As a synthetic material, production involves petrochemical feedstocks but requires relatively low energy input compared to some natural alternatives. The molecule’s potency means small quantities deliver significant olfactory impact, reducing overall environmental load per unit of fragrance.
Explore 1-Ethynylcyclohexyl acetate
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References
- Arctander, S. (1969). Perfume and Flavor Chemicals. Montclair, NJ.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID40863510
Physical Properties
| Molecular Weight | 166.22 g/mol🔬 EPA CompTox |
| Density | 1.007 g/cm^3🔬 EPA CTX |
| Boiling Point | 208 °C🔬 EPA CTX |
| Melting Point | 44.751 °C📊 OPERA |
| Flash Point | 82 °C🔬 EPA CTX |
| Refractive Index | 1.473 Dimensionless📊 OPERA |
| Molar Volume | 163.972 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.8 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 2.258 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.258 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.44 Log10 unitless📊 OPERA |
| Water Solubility | 0.004 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.17 mmHg🔬 EPA CTX |
| Viscosity | 3.585 cP📊 OPERA |
| Surface Tension | 34.243 dyn/cm📊 OPERA |
| Thermal Conductivity | 130.431 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 26.3 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 1 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 45.973 cm^3/mol📊 OPERA |
| Polarizability | 18.225 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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