Phenol, 4-butyl- (CAS 1638-22-8) — Woody Base Note Fragrance Ingredient
Phenol, 4-butyl-
CAS 1638-22-8
What Is Phenol, 4-butyl-?
Phenol, 4-butyl- is a synthetic aromatic compound used in niche perfumery for its unique phenolic character. It adds a medicinal, smoky depth to fragrances. While not common in mainstream products, it appears in avant-garde compositions where a bold, unconventional note is desired.
Safety Profile
PROFESSIONAL USEWhat Does Phenol, 4-butyl- Smell Like?
Phenol, 4-butyl- presents an intense medicinal punch reminiscent of hospital antiseptics, evolving into a leathery, tarry smokiness. The phenolic core dominates with a rubbery, industrial edge that slowly softens into a warm birch tar-like drydown. In dilution, it reveals unexpected nuances – hints of clove-like spice and a faintly animalic undertone that adds complexity to chypres and leather accords.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used in trace amounts to amplify the leather accord’s phenolic roughness, contrasting with the floral heart. Creates a daring, almost dangerous edge.
Provides a subtle phenolic depth beneath the opulent resins, adding contrast to the sweetness like incense ashes in a golden censer.
2D Molecular Structure
SMILES: CCCCC1=CC=C(O)C=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
Phenol, 4-butyl- is a para-substituted phenol where a butyl group replaces the hydrogen at the 4-position. This modification increases lipophilicity compared to phenol itself while maintaining reactive phenolic character. Industrially synthesized through Friedel-Crafts alkylation of phenol, the position-selective synthesis requires careful control to avoid polyalkylation byproducts.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow liquid |
|---|---|
| Boiling Point | 232-234 °C |
| Density | 0.98 g/cm³ |
| Refractive Index | 1.528 |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Leather Accords | 0.1-0.5% | Up to 1% | Provides phenolic backbone |
| Chypres | 0.05-0.2% | Up to 0.5% | Adds medicinal contrast |
Classic Accords
Tip: Always pre-dilute to 1% in ethanol before incorporation due to high potency.
Alternatives & Comparisons
Less aggressive phenolic alternative with similar medicinal character but softer drydown. Preferred when less tenacity is needed.
Offers phenolic smokiness with added vanilla-like sweetness from methoxy substitution. More versatile in oriental compositions.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA but recommended usage below 1% due to sensitization potential.
GHS Classification
RIFM Assessment
No formal RIFM assessment available. Handle with same precautions as other phenolics.
Sustainability
Synthesized from petrochemical precursors with moderate environmental impact. No known natural sources. Waste products require proper phenolic compound disposal protocols.
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References
- PubChem Compound Summary for 4-Butylphenol CID 7468
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 1638-22-8Physical Properties
| Molecular Weight | 150.22 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 3.4🔬 PubChem |
| Boiling Point | 248 °C🔬 EPA CompTox |
| Vapor Pressure | 0.0022 mmHg @ 25°C📊 OPERA |
| Flash Point | 121.5 °C🔬 EPA CompTox |
| Involatility Index | 0.0002💻 Calculated |
| log Kp (skin permeability) | -1.202💻 Calculated |
| SMILES | CCCCC1=CC=C(C=C1)O🔬 PubChem |
Volatility & Performance
| Fragrance Note | Base💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 4.8 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | spicywoody• leffingwell |
| Functional Groups | phenolaromatic💻 RDKit |
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: DTXSID3047425
Physical Properties
| Molecular Weight | 150.221 g/mol🔬 EPA CompTox |
| Density | 0.992 g/cm^3📊 OPERA |
| Boiling Point | 248 °C🔬 EPA CTX |
| Melting Point | 22 °C🔬 EPA CTX |
| Flash Point | 121.55 °C🔬 EPA CTX |
| Refractive Index | 1.523 Dimensionless📊 OPERA |
| Molar Volume | 153.694 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.63 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 3.523 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.523 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 7.44 Log10 unitless📊 OPERA |
| Water Solubility | 0.004 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.002 mmHg🔬 EPA CTX |
| Viscosity | 6.114 cP📊 OPERA |
| Surface Tension | 35.911 dyn/cm📊 OPERA |
| Thermal Conductivity | 141.987 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 | 3 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 46.949 cm^3/mol📊 OPERA |
| Polarizability | 18.612 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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