O-Propylphenol (CAS 644-35-9) — Mid Note Fragrance Ingredient
O-Propylphenol
CAS 644-35-9
What Is O-Propylphenol?
O-Propylphenol (CAS 644-35-9) is an aroma chemical used as a fragrance and flavour ingredient. Its odour is described as balsamic, medicinal and phenolic, placing it within the woody family as a mid note with low volatility. With a molecular weight of 136.2 (formula C9H12O), it is handled by perfumers as a building block for compositions where a balsamic character is desired. The data below is compiled from public chemical and regulatory sources.
Safety Profile
USE WITH AWARENESS
What Does O-Propylphenol Smell Like?
The odour profile of O-Propylphenol is reported as balsamic, medicinal, phenolic, smoky, spicy. The dominant facet is its balsamic character, with the remaining notes adding nuance and complexity. As a mid note it contributes to the heart of a fragrance. Perceived intensity and exact character depend on concentration, the carrier and the surrounding accord.
Scent Profile
Profile derived from public odour-descriptor data; relative, not absolute.
2D Molecular Structure
SMILES: CCCC1=C(O)C=CC=C1
Chemistry & Properties
The Chemistry
O-Propylphenol has the molecular formula C9H12O and a molecular weight of 136.2 g/mol. Its canonical SMILES representation is CCCC1=CC=CC=C1O. Its reported log P (XLogP) of 2.90 indicates a lipophilic, oil-soluble molecule, which informs how it partitions in a formula. Physical constants below are drawn from PubChem and EPA CompTox public datasets.
Physical & Chemical Properties
| Molecular Weight | 136.2 g/mol |
|---|---|
| Boiling Point | 220.0 °C |
| Melting Point | 7.00 °C |
| Flash Point | 92.51 °C |
| Density | 0.992 g/cm³ |
| Vapor Pressure | 0.0783 mmHg |
| Water Solubility | 0.015 g/L |
| XLogP | 2.90 |
Perfumer Guide
Alternatives & Comparisons
Ingredients occupying a similar odour space — useful as substitutes or companions when O-Propylphenol is unavailable or restricted.
Shares medicinal, phenolic, smoky character — a candidate substitute or companion in the same odour space.
Shares balsamic, leather, medicinal character — a candidate substitute or companion in the same odour space.
Shares leather, medicinal, phenolic character — a candidate substitute or companion in the same odour space.
Safety & Regulatory
⚠ Regulatory Disclaimer
General reference only. IFRA, REACH and EU Cosmetics Regulation standards update periodically. Consult the current IFRA Standards Library before formulating. Not legal or regulatory advice.
IFRA Status
No IFRA restriction recorded in the data set. This is not a guarantee of unrestricted status — always confirm against the current IFRA Standards Library.
GHS Classification
Signal word: Warning
Odour detection threshold (air): 0.007899 ppb — a literature-curated value indicating its potency in the vapour phase.
Open O-Propylphenol in Fragrance Studio (Pro) for the calibrated vapour-pressure curve, the modelled odour-threshold estimate, and the substitute-matching engine across 2,900+ aromachemicals.
References & Sources
- PubChem Compound Summary (NIH) — search by InChIKey
- EPA CompTox Chemicals Dashboard — physicochemical & fate data
- IFRA Standards Library (49th / 51st Amendment)
Data: PubChem (NIH), EPA CompTox, IFRA. Last reviewed: Jun 2026.
Ingredient Data Sheet
CAS 644-35-9Physical Properties
| Molecular Weight | 136.19 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 2.9🔬 PubChem |
| Boiling Point | 224 °C🔬 EPA CompTox |
| Vapor Pressure | 0.0873 mmHg @ 25°C📊 OPERA |
| Flash Point | 93 °C🔬 EPA CompTox |
| Involatility Index | 0.0081💻 Calculated |
| log Kp (skin permeability) | -1.472💻 Calculated |
| SMILES | CCCC1=CC=CC=C1O🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 1.8 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | balsamicmedicinalphenolicsmokyspicy• leffingwell |
| Functional Groups | phenolaromatic💻 RDKit |
| o-Propylphenol has a phenolic odor.📖 Fenaroli | |
Sensory Thresholds
| Odor Detection Threshold | 0.0479 ppm (n=3)📖 van Gemert |
Regulatory Status
| IOFI Classification | Nature Identical📖 Fenaroli |
Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.
Physicochemical Properties
DTXSID: DTXSID9047702
Physical Properties
| Molecular Weight | 136.194 g/mol🔬 EPA CompTox |
| Density | 0.986 g/cm^3🔬 EPA CTX |
| Boiling Point | 223.333 °C🔬 EPA CTX |
| Melting Point | 7 °C🔬 EPA CTX |
| Flash Point | 93 °C🔬 EPA CTX |
| Refractive Index | 1.529 Dimensionless📊 OPERA |
| Molar Volume | 137.187 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 2.93 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 2.948 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 2.948 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 7.15 Log10 unitless📊 OPERA |
| Water Solubility | 0.016 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.089 mmHg🔬 EPA CTX |
| Viscosity | 6.366 cP📊 OPERA |
| Surface Tension | 36.541 dyn/cm📊 OPERA |
| Thermal Conductivity | 143.387 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 20.23 Ų💻 Computed |
| H-Bond Donors | 1 count💻 Computed |
| H-Bond Acceptors | 1 count💻 Computed |
| Rotatable Bonds | 2 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 42.317 cm^3/mol📊 OPERA |
| Polarizability | 16.776 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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