Isobornyl propionate (CAS 2756-56-1) — Woody Top to Middle Note Fragrance Ingredient
Isobornyl propionate
CAS 2756-56-1
What Is Isobornyl propionate?
Isobornyl propionate is a synthetic fragrance ingredient used to add crisp, woody-pine notes to perfumes and scented products. You’ll encounter it in masculine colognes, forest-inspired body washes, and household cleaners seeking a fresh, outdoorsy character. This versatile molecule helps bridge bright top notes with deeper woody bases, creating scents that feel simultaneously clean and rugged.
Safety Profile
GENERALLY SAFEWhat Does Isobornyl propionate Smell Like?
Isobornyl propionate opens with a brisk, camphoraceous pine note reminiscent of freshly split lumber, quickly softening into a rounded woody character with subtle fruity undertones. As it dries, it reveals a clean, slightly sweet balsamic quality like sun-warmed tree resin, without the heaviness of traditional balsams. The dry-down maintains excellent diffusion, leaving a lingering impression of alpine air – crisp yet surprisingly smooth for such a vibrant woody note.
2D Molecular Structure
SMILES: [H][C@]12CC[C@@](C)([C@H](C1)OC(=O)CC)C2(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
Isobornyl propionate is an ester formed from isoborneol and propionic acid, belonging to the bicyclic monoterpenoid class. Industrially produced via esterification of isoborneol (itself derived from camphene), it lacks the variability of natural terpenes. The rigid bicyclic structure contributes to its excellent stability and resistance to oxidation compared to simpler terpene esters. While often used as a single isomer, minor impurities of related bornyl esters can influence its olfactory profile.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | ~230 °C (estimated) |
| Density | ~0.95 g/cm³ (estimated) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-5% | Up to 8% | Adds woody lift to fougères |
| Functional Products | 0.5-3% | Up to 5% | Clean pine effect in detergents |
| Body Care | 0.2-2% | Up to 3% | Sporty freshness in deodorants |
Classic Accords
Tip: Use with citrus top notes to prevent excessive sharpness in the dry-down.
Alternatives & Comparisons
Milder, more balsamic alternative with similar woody-pine character but lower odor intensity.
Softer floral-woody profile when a less camphoraceous effect is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not restricted under current IFRA standards (Amendment 49).
RIFM Assessment
Considered safe for current fragrance use levels based on RIFM’s 2015 evaluation.
Sustainability
As a fully synthetic material, isobornyl propionate avoids forestry impacts associated with natural pine derivatives. Its production from camphene (a turpentine byproduct) represents efficient utilization of paper industry waste streams. The esterification process typically employs green chemistry principles with high atom economy and minimal hazardous byproducts.
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Perfumer’s Notes
FEMA #: 2163
Isobornyl propionate has a characteristic, definite turpentine odor but less pungent than the corresponding acetate.
Odor: turpentine;fruit
MW: 210.31
LogP: 3.8
Physicochemical Properties
DTXSID: DTXSID2042062
Physical Properties
| Molecular Weight | 210.317 g/mol🔬 EPA CompTox |
| Density | 0.971 g/cm^3🔬 EPA CTX |
| Boiling Point | 248.1 °C🔬 EPA CTX |
| Melting Point | 42.975 °C📊 OPERA |
| Flash Point | 100 °C🔬 EPA CTX |
| Refractive Index | 1.48 Dimensionless📊 OPERA |
| Molar Volume | 211.114 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 5 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 4.143 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 4.143 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.83 Log10 unitless📊 OPERA |
| Water Solubility | 0 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.023 mmHg🔬 EPA CTX |
| Viscosity | 9.15 cP📊 OPERA |
| Surface Tension | 31.643 dyn/cm📊 OPERA |
| Thermal Conductivity | 115.809 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 | 59.978 cm^3/mol📊 OPERA |
| Polarizability | 23.777 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.
