Coumarin: Aroma Chemical Uses, Odour and Safety

Coumarin is the compound behind the smell of freshly cut hay and tonka beans. It was one of the first aroma chemicals used in modern perfumery and remains a backbone of fougère and oriental styles.

• Formula: C9H6O2, molar mass 146.14 g/mol
• CAS number: 91-64-5
• Appearance: white crystals or crystalline powder
• Melting point: about 71 °C; boiling point about 301 °C
• Solubility: poorly soluble in cold water; dissolves in ethanol and common perfumery solvents

Azlok lists Coumarin in its aromatic raw materials range, for perfume, soap, candle and incense work. The name doesn't state a pack size, so check it on the product page. It is not for food or flavour use. See today's price per kg.

• Fine fragrance: core of fougère accords with lavender and oakmoss-type notes; adds warmth to oriental and gourmand blends
• Soaps and detergents: sweet, stable note that holds up well in soap
• Incense and agarbatti: used in sweet, powdery masala and dhoop blends
• Candles and room fragrance: warm, hay-like base note

In a fougère, coumarin sits under lavender and a mossy, woody base and gives the classic barbershop smell. In gourmand styles it bridges vanilla and almond notes. It also helps cover harsh notes in soap bases, which is one reason it turns up so often in toiletries. Unlike vanillin, it doesn't turn soap brown, so it is useful in light-coloured bars.

Because it's a solid, perfumers usually make a stock solution first. A 10% solution in perfumer's alcohol (ethanol) or dipropylene glycol (DPG) is common: 10 g coumarin to 90 g solvent, stirred until clear. Warm gently if it is slow to dissolve.

Smell it on a blotter at 10% and again after a few hours. It is a long-lasting base note and is often used with vanillin, lavender and musks. For any product to be applied to skin, check current IFRA standards for coumarin limits and keep a record of how much you've used.

Handle with gloves and avoid breathing the dust. Coumarin is a known fragrance allergen; in the EU it must be named on cosmetic labels above set thresholds, so it's worth tracking even for products sold in India.

• Not for eating or flavouring food.
• Store tightly closed, away from light and heat.
• Keep away from children.
• Sweep up spills dry, avoiding dust.
• If crystals form in your stock solution during winter, warm the bottle in a water bath and shake before use.

For home perfumery and testing, a small pack lasts a long time, since it's used in small amounts. Incense and soap makers using it every week can move to larger packs. For fine fragrance, ask for a certificate of analysis. For 25 kg and above, send a bulk inquiry.