Guaiacol (CAS 90-05-1) — Smoky Heart Note Fragrance Ingredient
Guaiacol
CAS 90-05-1
What Is Guaiacol?
Guaiacol is a naturally occurring compound found in wood smoke and certain essential oils like guaiac wood. People encounter its distinctive smoky aroma in barbecue, smoked foods, and some perfumes. This ingredient matters because it adds depth and warmth to fragrances, creating evocative campfire or leather-like accords that are both nostalgic and sophisticated.
Safety Profile
USE WITH AWARENESS
What Does Guaiacol Smell Like?
Guaiacol announces itself with an intense, phenolic smokiness reminiscent of charred oak barrels and smoldering embers. The initial medicinal sharpness softens into a heart of leathery warmth with subtle vanilla undertones. As it dries down, it reveals a complex interplay of woody sweetness and creosote-like depth, leaving a lingering trail that evokes aged whiskey and fine cigars. The transformation from harsh smoke to refined warmth makes it invaluable for creating sophisticated smoky accords.
Scent Profile
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Guaiacol forms the smoky backbone of this fragrance, blending with incense and cedar to create a meditative bonfire effect that’s both spiritual and sensual.
Here guaiacol’s smoky character evokes campfire memories, combining with leather and spices for a rugged Western aesthetic.
Guaiacol provides the photorealistic woodsmoke note that makes this winter favorite so comforting and nostalgic.
2D Molecular Structure
SMILES: COC1=C(O)C=CC=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
Guaiacol is a methoxyphenol, structurally related to both phenol and anisole. It occurs naturally in the pyrolysis of lignin, particularly in guaiacum wood and creosote. Industrially, it’s produced by methylation of catechol or demethylation of vanillin. The methoxy group adjacent to the hydroxyl creates unique reactivity, allowing it to participate in both electrophilic aromatic substitution and hydrogen bonding. This bifunctional nature contributes to its distinctive odor profile and moderate volatility.
Physical & Chemical Properties
| Boiling Point | 205 °C |
|---|---|
| Melting Point | 28-32 °C |
| Density | 1.112 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Powerful smoky modifier |
| Functional Fragrance | 0.01-0.1% | Up to 0.2% | Used sparingly in air care |
Classic Accords
+ Birch Tar + Leather = Russian Leather
+ Vetiver + Patchouli = Dark Earth
Tip: Balance guaiacol’s intensity with sweet or balsamic materials to prevent harshness.
Alternatives & Comparisons
A more complex smoky profile from wood tar, but with greater variability in composition and stronger medicinal facets.
Offers similar phenolic warmth but with more floral-spicy character and less aggressive smokiness.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. IFRA, REACH, EU Cosmetics Regulation standards update periodically. Consult current IFRA Standards Library before formulating. Not legal or regulatory advice.
IFRA Status
No IFRA restrictions currently apply to guaiacol (as of 51st Amendment).
EU Allergen Declaration
Not listed as an EU allergen.
GHS Classification
H315 Causes skin irritation
H319 Causes serious eye irritation
RIFM Assessment
RIFM evaluation confirms safe use at current industry levels with proper precautions.
Sustainability
Most commercial guaiacol is now synthesized from renewable lignin sources rather than extracted from endangered guaiacum trees. Synthetic production avoids deforestation pressures while maintaining consistent quality. The compound is readily biodegradable under environmental conditions.
Explore Guaiacol
Browse essential oils and aroma compounds.
Affiliate disclosure: we may earn a small commission at no extra cost to you.
Industry & Science Data
References
- Burdock, G.A. (2010). Fenaroli’s Handbook of Flavor Ingredients. CRC Press. ISBN 9781420090869
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Mar 2026.
Ingredient Data Sheet
CAS 90-05-1Physical Properties
| Molecular Weight | 124.14 g/mol🔬 PubChem |
| LogP (Octanol-Water) | 1.3🔬 PubChem |
| Boiling Point | 203.9 °C🔬 EPA CompTox |
| Vapor Pressure | 5 mmHg @ 25°C📊 OPERA |
| Flash Point | 82.2 °C🔬 EPA CompTox |
| Involatility Index | 0.4837💻 Calculated |
| log Kp (skin permeability) | -2.534💻 Calculated |
| SMILES | COC1=CC=CC=C1O🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Moderate💻 Calculated |
| Persistence Score | 0.5 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | medicinalphenolicsmokysweetvanilla• leffingwell |
| Functional Groups | phenoletheraromatic💻 RDKit |
| “Powerful smoke-like, somewhat medicinal odor, sweeter than the prototype phenolic odor.”📖 Arctander | |
| Guaiacol has a characteristic sweet odor. It is slightly phenolic.📖 Fenaroli | |
Flavor Notes (Arctander)
| “Warm, medicinal and somewhat sweet taste, but accompanied by a burning sensation, even in high dilution. Guaiacol finds some application in flavor compositions, such as imitation Coffee, Vanilla, Whisky (smokey effect), Tobacco, Rum, etc. and in many fruit and Spice complexes.”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 0.0269 ppm (n=23)📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2532⚖️ FEMA GRAS |
| GRAS Status | Generally Recognized as Safe⚖️ FEMA GRAS |
| 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: DTXSID0023113
Physical Properties
| Molecular Weight | 124.139 g/mol🔬 EPA CompTox |
| Density | 1.123 g/cm^3🔬 EPA CTX |
| Boiling Point | 205 °C🔬 EPA CTX |
| Melting Point | 29.5 °C🔬 EPA CTX |
| Flash Point | 82.168 °C🔬 EPA CTX |
| Refractive Index | 1.535 Dimensionless📊 OPERA |
| Molar Volume | 111.866 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.328 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 1.329 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.328 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.91 Log10 unitless📊 OPERA |
| Water Solubility | 0.089 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 0.103 mmHg🔬 EPA CTX |
| Viscosity | 6.671 cP📊 OPERA |
| Surface Tension | 37.636 dyn/cm📊 OPERA |
| Thermal Conductivity | 152.549 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 29.46 Ų💻 Computed |
| H-Bond Donors | 1 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 1 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 34.813 cm^3/mol📊 OPERA |
| Polarizability | 13.801 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.
Related Research
- (Z)-beta-1-(2,6,6-Trimethyl-1-cyclohexen-1-yl)-2-buten-1-one (CAS 23726-92-3) — Floral Top Note Fragrance Ingredient
- 2,4-Dimethylcyclohexylmethyl acetate (CAS 67634-22-4) — Woody Middle Note Fragrance Ingredient
- 2-Heptanol (CAS 543-49-7) — Green Top-middle Note Fragrance Ingredient
- beta-dodecylseleno-gamma-damascone (CAS 2432005-07-5) — Sweet Heart to base Note Fragrance Ingredient
![4H-4a,9-Methanoazuleno[5,6-d]-1,3-dioxole, octahydro-2,2,5,8,8,9a-hexamethyl-, (4aR,5R,7aS,9R)- (CAS 211299-54-6) — Woody Base Note Fragrance Ingredient](https://thegoodscents.company/wp-content/uploads/2026/04/4h-4a-9-methanoazuleno-5-6-d-1-3-dioxole-octahydro-2-2-5-8-8-1-768x439.webp)
