2-tert-Butyl-p-cresol (CAS 2409-55-4) — Woody Base Note Fragrance Ingredient
2-tert-Butyl-p-cresol
CAS 2409-55-4
What Is 2-tert-Butyl-p-cresol?
2-tert-Butyl-p-cresol is a synthetic aromatic compound used as a fixative in perfumes and industrial applications. You might encounter it in leathery or woody fragrances where it adds stability. This ingredient matters because it helps fragrances last longer on skin, acting as an invisible backbone that prevents top notes from evaporating too quickly.
Safety Profile
USE WITH AWARENESSWhat Does 2-tert-Butyl-p-cresol Smell Like?
2-tert-Butyl-p-cresol presents a complex aromatic profile – imagine the phenolic sharpness of hospital antiseptics mellowed by time, evolving into a dry, woody character reminiscent of sun-baked driftwood. Its initial medicinal punch gives way to a persistent, slightly smoky base that lingers close to the skin. The dry-down reveals subtle leathery undertones that work exceptionally well in masculine accords.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used sparingly to enhance the leather accord, providing phenolic depth that mimics traditional Russian leather tanning methods.
Contributes to the legendary petrol-leather opening, adding industrial realism to this historic masculine fragrance.
2D Molecular Structure
SMILES: CC1=CC(=C(O)C=C1)C(C)(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
2-tert-Butyl-p-cresol belongs to the alkylphenol class, synthesized through Friedel-Crafts alkylation of p-cresol with isobutylene. The bulky tert-butyl group ortho to the hydroxyl creates steric hindrance that increases stability. Industrially produced via acid-catalyzed reactions, this compound exhibits typical phenolic properties with reduced reactivity compared to simpler phenols due to its substituted structure.
Physical & Chemical Properties
| Appearance | Colorless to pale yellow crystals |
|---|---|
| Melting Point | 52-54 °C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Used as fixative in leather accords |
| Functional Fragrance | 0.05-0.2% | Up to 0.5% | Adds phenolic character to cleaning products |
Classic Accords
Tip: Use in trace amounts with ionones to create subtle leather effects without overwhelming phenolic character.
Alternatives & Comparisons
Less sterically hindered phenol with sharper medicinal character, useful when more phenolic punch is desired.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not currently restricted by IFRA standards.
GHS Classification
RIFM Assessment
RIFM has evaluated similar alkylphenols but specific data on this compound is limited – use precautionary principles.
Sustainability
As a synthetic material, production relies on petrochemical feedstocks. No known major environmental concerns at current usage levels, but phenolic compounds require careful wastewater management during manufacturing.
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Ingredient Data Sheet
CAS 2409-55-4Physical Properties
| Molecular Weight | 164.24 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 3.6🔬 PubChem |
| Boiling Point | 237 °C🔬 EPA CompTox |
| Vapor Pressure | 0.02 mmHg @ 25°C📊 OPERA |
| Flash Point | 105 °C🔬 EPA CompTox |
| Involatility Index | 0.0017💻 Calculated |
| log Kp (skin permeability) | -1.146💻 Calculated |
| SMILES | CC1=CC(=C(C=C1)O)C(C)(C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Heart💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 3.2 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | balsamicwoody• leffingwell |
| Functional Groups | phenolaromatic💻 RDKit |
Sensory Thresholds
| Odor Detection Threshold | 0.03 ppm📖 van Gemert |
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: DTXSID2020212
Physical Properties
| Molecular Weight | 164.248 g/mol🔬 EPA CompTox |
| Density | 0.96 g/cm^3🔬 EPA CTX |
| Boiling Point | 236 °C🔬 EPA CTX |
| Melting Point | 51.5 °C🔬 EPA CTX |
| Flash Point | 104.7 °C🔬 EPA CTX |
| Refractive Index | 1.513 Dimensionless📊 OPERA |
| Molar Volume | 170.826 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 3.8 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 3.552 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 3.552 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 7.71 Log10 unitless📊 OPERA |
| Water Solubility | 0.002 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.029 mmHg🔬 EPA CTX |
| Viscosity | 5.202 cP📊 OPERA |
| Surface Tension | 32.233 dyn/cm📊 OPERA |
| Thermal Conductivity | 126.338 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 | 0 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 51.347 cm^3/mol📊 OPERA |
| Polarizability | 20.355 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.
