In short
Coumarin occurs naturally in tonka beans and many plants and is made synthetically for perfumery. It gives the sweet, hay-like smell that defines fougère fragrances.
What Coumarin smells like
Coumarin is the classic odour of new-mown hay. Perfumer & Flavorist describes it as sweet and aromatic, with creamy vanilla-bean and nut-like tones that are heavy rather than sharp; The Good Scents Company lists sweet, hay, tonka and new-mown hay. It is the dominant odorant of tonka beans and forms in grasses only when they are cut and dried. Beside dihydrocoumarin it gives a cleaner, more direct almond-hay note.
- Leading note
- Sweet hay
- Clear facets
- Tonka, vanilla-bean
- Supporting facets
- Almond, nutty
- Faint facets
- Tobacco
- Character
- Warm, sweet, powdery, heavy
What makes Coumarin distinctive
Hay drying in the sun: sweet and almond-nutty, the backbone of the fougère.
How Coumarin is used
Used as the base of fougère accords, and in oriental, tobacco, gourmand and powdery compositions. IFRA restricts it.
Typical role: backbone (used in large proportions as a structural material of an accord); fixative (slow to evaporate; helps a blend last and holds lighter notes).
How Coumarin differs from similar materials
- Dihydrocoumarin
- Dihydrocoumarin is creamier, with coconut, herbal and balsamic notes; coumarin is the cleaner, more direct hay and almond. (compared directly by a cited source)
- Tonka Bean Absolute
- Tonka absolute is largely coumarin, and adds caramel, prune, almond and tobacco around it. (compared directly by a cited source)
- Hay Absolute
- Hay absolute adds herbaceous, fig-jam, honey and tobacco notes to coumarin's hay.
- Heliotropin
- Heliotropin is powdery almond-heliotrope without the hay; coumarin is hay-like and tonka-sweet.
- Dimethyl Hydroquinone
- Dimethyl hydroquinone is an intensely sweet floral with nutty, sweet-clover notes; coumarin is the sweet hay with almond and tonka.
An asterisk marks a difference that a cited source states directly. The others compare the published descriptions of each material. Smell varies with grade, supplier and dilution; compare them side by side on blotters before substituting one for another.
Formulation considerations
A crystalline solid; dissolve before use. A declarable allergen covered by an IFRA Standard.
Identity and classification
- Type
- Aroma chemical
- Origin
- Occurs in nature
- Odour family
- Powdery / Fougère
- Note position
- Base note
- Physical form at room temperature
- Solid
- CAS number
- 91-64-5
- Molecular formula
- C9H6O2
- Molecular weight
- 146.14 g/mol
- IUPAC name
- chromen-2-one
The CAS number, formula and molecular weight are taken from PubChem compound 323, whose own record lists this CAS number; checked 19 October 2026.
Safety and compliance
The IFRA Standards Library lists a Standard covering Coumarin:
- "Coumarin" — Restriction, 49th Amendment, published 2020-01
Limits differ by product category and are set out in the Standard itself; this page does not reproduce them. The list above reflects the library as read on 19 October 2026.
Coumarin is one of the 26 fragrance allergens listed individually in Annex III of the EU Cosmetics Regulation (label name: Coumarin), which must be named on cosmetic labels above 0.001% in leave-on and 0.01% in rinse-off products. Regulation (EU) 2023/1545 extended the list; see the fragrance allergens list.
Hazard classification of the neat substance, as PubChem summarises it, read 26 October 2026. Companies notifying the ECHA C&L Inventory classify it (2,825 reports): H317 may cause an allergic skin reaction (92.9% of reports); H302 harmful if swallowed (84.5% of reports); H301 toxic if swallowed (12.1% of reports). 43 of the reports find it does not meet the hazard criteria. A skin sensitiser classification concerns handling the neat material and the dose in a finished product; the IFRA Standards, where they apply, set the limits. Unless it is harmonised, this is the notifiers' own classification, not a binding one.
This page is general information, not a safety assessment or a specification. Confirm identity, composition, IFRA status and allergen content from your supplier's documents for the lot you hold.
Materials it works with
-
Lavender Oil
Essential oil · Aromatic / Floral — lavender, herbal, floral, fresh
-
Oakmoss Absolute
Absolute · Chypre / Green — mossy, earthy, inky, forest floor
-
Vanillin
Aroma chemical · Gourmand / Amber — vanilla, sweet, creamy
-
Tonka Bean Absolute
Absolute · Gourmand / Powdery — coumarinic, hay, almond, sweet
-
Heliotropin
Aroma chemical · Powdery / Gourmand — powdery, almond, vanilla, floral
Coumarin is also suggested as a partner on the pages for delta-Undecalactone, Dimethyl Hydroquinone, Dulcinyl, gamma-Hexalactone, Lavandin Absolute and Lavender Aldehyde.
Used in formulas and accords
Used in 62 published formulas
Coumarin is an ingredient in 28 perfume formulas, 31 accords and 3 bases in the Formula & Accord Library.
Community formulas
RUŌOD House Originals
Original compositions by RUŌOD House.
Further reading
Questions about Coumarin
Is Coumarin natural or synthetic?
The molecule occurs in nature. Commercial Coumarin may be made by synthesis or obtained from natural sources, so check the supplier's specification if the distinction matters to you.
What is the CAS number of Coumarin?
91-64-5. It was checked against PubChem on 19 October 2026.
Which published formulas use Coumarin?
Coumarin is used in 62 published formulas in the RUŌOD Lab Formula & Accord Library, including Amber Accord, Anise Ink and Banana Bread. Each is listed with a link under "Used in formulas and accords" on this page.
Is Coumarin covered by an IFRA Standard?
Yes. The IFRA Standards Library lists a Standard covering it: "Coumarin" — Restriction, 49th Amendment. The limits depend on the product category; read the Standard itself before formulating.
Sources
- PubChem — compound 323, checked 19 October 2026.
- PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
- IFRA — Standards Library, read 19 October 2026.
- EUR-Lex — Regulation (EC) No 1223/2009, Annex III.
- Perfumer & Flavorist — Coumarin — published literature.
- Britannica — Coumarin — published perfumery reference.
- The Good Scents Company — coumarinic odour category — odour database.
- Olfactory profile: the RUŌOD Lab team's synthesis of the published descriptions above, reviewed 21 October 2026. Evidence: several independent published descriptions, which agree. Classification and the short description: revision 1. Descriptions of odour are judgement, not measurement.