Guaiazulene (CAS 489-84-9) — Woody Heart Note Fragrance Ingredient
Guaiazulene
CAS 489-84-9
What Is Guaiazulene?
Guaiazulene is a deep blue aromatic compound originally derived from guaiac wood oil, now mostly synthesized. It appears in niche perfumes and skincare for its striking color and subtle woody-earthy scent. This rare ingredient matters because it provides both visual drama and a smooth, slightly medicinal aroma profile that perfumers use to add depth to modern compositions.
Safety Profile
GENERALLY SAFE
What Does Guaiazulene Smell Like?
Guaiazulene greets the nose with a cool, faintly camphoraceous whisper reminiscent of antique apothecary cabinets. As it unfolds, the scent reveals dry cedar shavings and distant wood smoke, with a peculiar mineral edge like wet slate. The dry-down lingers as a soft, earthy hum—imagine the scent left on your hands after handling well-aged hardwood. Though subtle in projection, it adds remarkable tenacity and chromatic intrigue to fragrances.
Scent Profile
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Used here for its visual impact and dry woody facets that enhance the incense accord, creating a meditative blue-hued smokiness.
The azure color provides visual theater while the molecule’s mild antiseptic quality tempers sweet amber notes.
2D Molecular Structure
SMILES: CC(C)C1=CC2=C(C)C=CC2=C(C)C=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
Guaiazulene is a sesquiterpene with a unique azulene skeleton, isomeric with naphthalene. First isolated from guaiac wood oil, modern production involves synthesis from vetivazulene or dehydrogenation of sesquiterpenes. The conjugated 7-membered ring system creates its signature blue color and stability against oxidation. Unlike most aromatic compounds, it’s non-benzoid with distinctive electron distribution that influences both its hue and mild polarity.
Physical & Chemical Properties
| Appearance | Deep blue crystalline solid |
|---|---|
| Melting Point | 31-33 °C |
| Boiling Point | 153 °C (0.05 mmHg) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Colorant | 0.01-0.1% | Up to 0.5% | Primarily for visual effect |
| Fragrance | 0.5-2% | Up to 3% | Adds dry woody facets |
Classic Accords
+ Ambergris + Sea Notes = Oceanic Mineral
Tip: Dissolve in ethanol before adding to oil phases to prevent speckling.
Alternatives & Comparisons
Similar blue colorant from chamomile with gentler, herbal aroma for sensitive applications.
More greenish hue and pronounced rooty-earthy scent for darker compositions.
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
Not restricted by IFRA. Listed as colorant CI 75130.
RIFM Assessment
RIFM assessment confirms safe use at current levels in fragrance applications.
Sustainability
Historically extracted from endangered guaiacum trees, modern synthesis from renewable terpene sources reduces ecological impact. The manufacturing process requires careful solvent management, but the molecule’s stability and potency result in low environmental load per use.
Explore Guaiazulene
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Industry & Science Data
References
- Surburg & Panten (2006). Common Fragrance and Flavor Materials.
- PubChem Guaiazulene CID 3515
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Mar 2026.
Physicochemical Properties
DTXSID: DTXSID7045996
Physical Properties
| Molecular Weight | 198.309 g/mol🔬 EPA CompTox |
| Density | 0.97 g/cm^3🔬 EPA CTX |
| Boiling Point | 296.151 °C📊 OPERA |
| Melting Point | 31.722 °C🔬 EPA CTX |
| Flash Point | 113.05 °C🔬 EPA CTX |
| Refractive Index | 1.573 Dimensionless📊 OPERA |
| Molar Volume | 206.172 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 5.19 Log10 unitless📊 OPERA |
| LogD (pH 5.5) | 5.19 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 5.19 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 7.43 Log10 unitless📊 OPERA |
| Water Solubility | 0 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0.001 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0.002 mmHg📊 OPERA |
| Viscosity | 10.281 cP📊 OPERA |
| Surface Tension | 34.848 dyn/cm📊 OPERA |
| Thermal Conductivity | 115.84 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 | 1 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 67.93 cm^3/mol📊 OPERA |
| Polarizability | 26.93 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.
