Coumarin (CAS 91-64-5) — Sweet Base Note Fragrance Ingredient
Coumarin
CAS 91-64-5
What Is Coumarin?
Coumarin is a sweet-smelling compound found naturally in tonka beans, vanilla grass, and sweet clover. It’s used in perfumes, soaps, and flavorings. While it creates warm, comforting scents, some people may be sensitive to it, so check product labels if you have allergies.
Safety Profile
USE WITH AWARENESS
What Does Coumarin Smell Like?
Coumarin delivers a rich, sweet aroma reminiscent of freshly cut hay with vanilla undertones. Initially sharp and herbaceous, it mellows into a warm, nutty sweetness that lingers. The dry-down reveals a creamy, almond-like character that blends beautifully with woody and spicy notes.
Scent Profile
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
Coumarin provides the sweet, hay-like foundation that blends with lavender and vanilla, creating one of the first modern fougère accords.
Used as a key ingredient to craft the sweet, herbaceous heart of this pioneering fougère fragrance.
2D Molecular Structure
SMILES: O=C1OC2=C(C=CC=C2)C=C1
Chemistry, Properties & Perfumer Guide
The Chemistry
Coumarin is a benzopyrone compound naturally occurring in many plants. It can be synthesized from salicylaldehyde or extracted from natural sources. The molecule’s planar structure and conjugated system contribute to its stability and characteristic odor profile.
Physical & Chemical Properties
| Boiling Point | 301 °C |
|---|---|
| Melting Point | 68-70 °C |
| Density | 0.935 g/cm³ |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.5-2% | Up to 3.9% | Fougère and oriental accords |
| Soap/Detergent | 0.1-0.5% | Up to 1% | Adds warmth to clean scents |
Classic Accords
+ Vanilla + Tonka = Gourmand
Tip: Use coumarin to add sweet depth without overwhelming floral or citrus top notes.
Alternatives & Comparisons
A hydrogenated version with similar scent profile but greater stability in alkaline formulations.
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
IFRA restricted to 3.9% in leave-on products (Amendment 49).
EU Allergen Declaration
Must be declared when present at ≥0.001% in leave-on products.
GHS Classification
H315 Causes skin irritation
RIFM Assessment
RIFM assessment confirms safe use at current restricted levels.
Sustainability
Most commercial coumarin is now synthesized, reducing pressure on natural sources like tonka beans. Synthetic production has lower environmental impact than agricultural harvesting.
Explore Coumarin
Browse essential oils and aroma compounds.
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Industry & Science Data
References
- Bickers et al. (2005). Safety assessment of coumarin. International Journal of Toxicology. PMID 16126615
- PubChem Coumarin CID 323
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Mar 2026.
Physicochemical Properties
DTXSID: DTXSID7020348
Physical Properties
| Molecular Weight | 146.145 g/mol🔬 EPA CompTox |
| Density | 0.749 g/cm^3🔬 EPA CTX |
| Boiling Point | 299.733 °C🔬 EPA CTX |
| Melting Point | 70.138 °C🔬 EPA CTX |
| Flash Point | 155.473 °C🔬 EPA CTX |
| Refractive Index | 1.595 Dimensionless📊 OPERA |
| Molar Volume | 117.097 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | 1.439 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | 1.62 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | 1.62 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 5.72 Log10 unitless📊 OPERA |
| Water Solubility | 0.014 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 0.001 mmHg🔬 EPA CTX |
| Viscosity | 3.378 cP📊 OPERA |
| Surface Tension | 46.411 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 30.21 Ų💻 Computed |
| H-Bond Donors | 0 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 2 count💻 Computed |
| Molar Refractivity | 39.767 cm^3/mol📊 OPERA |
| Polarizability | 15.765 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.
