5-Ethylidenebicyclo[2.2.1]hept-2-yl propionate (CAS 73347-77-0) — Woody Middle Note Fragrance Ingredient
5-Ethylidenebicyclo[2.2.1]hept-2-yl propionate
CAS 73347-77-0
What Is 5-Ethylidenebicyclo[2.2.1]hept-2-yl propionate?
5-Ethylidenebicyclo[2.2.1]hept-2-yl propionate is a synthetic fragrance ingredient used in modern perfumery. It provides unique woody-green accents with subtle fruity undertones. Consumers may encounter it in niche fragrances where innovative scent profiles are desired. This compound matters because it represents the perfumer’s palette expanding through organic chemistry, allowing for novel olfactory experiences that don’t exist in nature.
Safety Profile
USE WITH AWARENESSWhat Does 5-Ethylidenebicyclo[2.2.1]hept-2-yl propionate Smell Like?
This synthetic molecule opens with a crisp, green-woody character reminiscent of freshly snapped twigs and damp forest floors. The initial sharpness gradually softens into a subtle fruity undertone, like unripe pear skins. Over time, it develops a faintly balsamic quality that lingers close to the skin. The dry-down reveals a clean, almost metallic woodiness that provides excellent diffusion without overwhelming.
2D Molecular Structure
SMILES: CCC(=O)OC1CC2CC1CC2=CC
Chemistry, Properties & Perfumer Guide
The Chemistry
5-Ethylidenebicyclo[2.2.1]hept-2-yl propionate is a bicyclic ester with a propionate group attached to a norbornene derivative. The ethylidene substituent introduces steric hindrance that affects volatility and odor characteristics. This compound is synthesized through Diels-Alder reactions followed by esterification. The rigid bicyclic structure contributes to its tenacious woody character while the ester group provides subtle fruity nuances.
Physical & Chemical Properties
| Molecular Weight | Not publicly available |
|---|---|
| Boiling Point | Not publicly available |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 5% | Used for woody-modern accords |
| Functional Fragrance | 0.1-1% | Up to 3% | Provides clean woody notes |
Classic Accords
Tip: Use to add structural woodiness to contemporary fragrances.
Alternatives & Comparisons
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA.
RIFM Assessment
No RIFM safety assessment publicly available.
Sustainability
As a synthetic material, this compound’s environmental impact depends on production methods. Being petroleum-derived, its sustainability is tied to the fragrance industry’s transition to greener chemistry. The complex synthesis suggests higher energy requirements compared to simpler fragrance molecules.
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References
- PubChem Compound Summary CID Not Available
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID00868248
Physical Properties
| Molecular Weight | 194.274 g/mol🔬 EPA CompTox |
| Density | 1.048 g/cm^3📊 OPERA |
| Boiling Point | 247.191 °C📊 OPERA |
| Melting Point | 30.279 °C📊 OPERA |
| Flash Point | 110.724 °C📊 OPERA |
| Refractive Index | 1.498 Dimensionless📊 OPERA |
| Molar Volume | 187.712 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.176 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 3.176 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.176 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.95 Log10 unitless📊 OPERA |
| Water Solubility | 0.009 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.013 mmHg📊 OPERA |
| Viscosity | 7.01 cP📊 OPERA |
| Surface Tension | 32.892 dyn/cm📊 OPERA |
| Thermal Conductivity | 127.526 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 | 2 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 54.992 cm^3/mol📊 OPERA |
| Polarizability | 21.801 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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