4-tert-Butyltoluene (CAS 98-51-1) — Woody Base Note Fragrance Ingredient
4-tert-Butyltoluene
CAS 98-51-1
What Is 4-tert-Butyltoluene?
4-tert-Butyltoluene is a synthetic aromatic compound used in fragrances to add woody, slightly sweet nuances. You’ll encounter it in masculine colognes and some household products. This ingredient matters because it provides long-lasting base notes while blending seamlessly with other woody and amber materials.
Safety Profile
USE WITH AWARENESSWhat Does 4-tert-Butyltoluene Smell Like?
4-tert-Butyltoluene presents a dry, woody aroma reminiscent of freshly planed cedar with subtle sweet undertones. Its scent profile evolves from an initial sharp, almost camphoraceous top note to a warm, ambery heart. The dry-down reveals a persistent woody-balsamic character that anchors fragrance compositions. Compared to simpler toluenes, the tert-butyl group adds depth and tenacity while maintaining excellent diffusion.
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used as a woody-modifier in the base, contributing to the fragrance’s mineral-earth accord while enhancing the vetiver and benzoin notes.
Provides subtle woody backbone to the ambroxan-heavy base, helping bridge the citrus top notes to the musky dry-down.
2D Molecular Structure
SMILES: CC1=CC=C(C=C1)C(C)(C)C
Chemistry, Properties & Perfumer Guide
The Chemistry
4-tert-Butyltoluene belongs to the alkylbenzene class, synthesized through Friedel-Crafts alkylation of toluene with isobutylene. The tert-butyl group creates steric hindrance that influences both odor properties and chemical reactivity. Unlike simpler toluenes, this branched structure resists oxidation while maintaining good volatility for a base note material.
Physical & Chemical Properties
| Boiling Point | 193-195 °C |
|---|---|
| Density | 0.857 g/cm³ |
| Flash Point | 65 °C |
| Vapor Pressure | 0.4 mmHg at 25°C |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 1-3% | Up to 5% | Woody base note enhancer |
| Functional Fragrances | 0.5-1% | Up to 2% | Provides longevity in detergents |
Classic Accords
Tip: Use with citrus top notes to create contrast and enhance perceived freshness.
Alternatives & Comparisons
Offers similar woody character but with fresher, more citrusy aspects due to the isopropyl group instead of tert-butyl.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No specific restrictions under current IFRA standards (Amendment 49).
GHS Classification
RIFM Assessment
RIFM evaluation complete – safe for use at current industry levels.
Sustainability
As a petroleum-derived synthetic, 4-tert-Butyltoluene has higher carbon footprint than natural alternatives. However, its efficient synthesis and long-lasting properties reduce overall usage quantities in formulations.
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References
- Bauer et al. (2001). Common Fragrance and Flavor Materials. Wiley-VCH.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorIngredient Data Sheet
CAS 98-51-1Physical Properties
| Molecular Weight | 148.24 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 4.5🔬 PubChem |
| Boiling Point | 192.8 °C🔬 EPA CompTox |
| Vapor Pressure | 1 mmHg @ 25°C📊 OPERA |
| Flash Point | 57.8 °C🔬 EPA CompTox |
| Involatility Index | 0.0885💻 Calculated |
| log Kp (skin permeability) | -0.409💻 Calculated |
| SMILES | CC1=CC=C(C=C1)C(C)(C)C🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Slow💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | balsamicwoody• leffingwell |
| Functional Groups | aromatic💻 RDKit |
Sensory Thresholds
| Odor Detection Threshold | 30.5 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: DTXSID1024704
Physical Properties
| Molecular Weight | 148.249 g/mol🔬 EPA CompTox |
| Density | 0.861 g/cm^3🔬 EPA CTX |
| Boiling Point | 192.344 °C🔬 EPA CTX |
| Melting Point | -55.454 °C🔬 EPA CTX |
| Flash Point | 61.752 °C🔬 EPA CTX |
| Refractive Index | 1.486 Dimensionless📊 OPERA |
| Molar Volume | 172.396 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 5.011 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 4.849 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 4.849 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 4.82 Log10 unitless📊 OPERA |
| Water Solubility | 0 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0.008 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.735 mmHg🔬 EPA CTX |
| Viscosity | 1.906 cP📊 OPERA |
| Surface Tension | 28.187 dyn/cm📊 OPERA |
| Thermal Conductivity | 116.785 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 0 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 0 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 49.465 cm^3/mol📊 OPERA |
| Polarizability | 19.609 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.
