Aldehydes

Aldehydes in perfume are a family of aroma chemicals, mostly the aliphatic (straight-chain) aldehydes C-8 to C-12, that give a fragrance a bright, fizzy, soapy lift. They smell waxy, metallic and clean, a little like a snuffed candle, freshly ironed cotton or the peel of an orange, and they are the signature of the aldehydic floral style made famous in the 1920s.

What does Aldehydes smell like?

Neat, the fatty aldehydes are sharp: waxy, citrusy, metallic and slightly fatty, with a champagne-like fizz. Each chain length differs: C-10 (decanal) leans towards orange peel, C-11 undecylenic is clean and airy, C-12 lauric is waxy with a hint of violet, and C-12 MNA (methyl nonyl acetaldehyde) has an ambery, pine-needle and incense-like edge. At perfume doses they rarely read as a note in their own right; they make surrounding flowers brighter and more diffusive and add a powdery, soapy, clean-skin feel.

Where Aldehydes comes from

Some aldehydes occur naturally in citrus peel, coriander and rose, but perfumery grades are synthetic and are handled heavily diluted because they are so powerful.

Also known as: Fatty aldehydes, aliphatic aldehydes, aldehyde C-10, C-11, C-12
Fragrance family: Aldehydic (usually within florals)
Type: Synthetic (some also occur in natural oils)
How it's obtained: Chemical synthesis
Key aroma molecules: Decanal, undecanal, undecylenic aldehyde, lauric aldehyde (dodecanal), 2-methylundecanal

Aldehydes in perfume history

Aliphatic aldehydes were first explored by perfumers in the early 20th century, but the style is forever linked with Chanel No. 5 (1921), in which Ernest Beaux used an unprecedented overdose of them over jasmine and rose. The result smelled abstract and modern rather than like any single flower, and it launched a family of aldehydic florals, including Lanvin Arpège (1927), and later Yves Saint Laurent Rive Gauche (1971) and Estée Lauder White Linen (1978).

Aldehydes in modern perfumery

Full-blown aldehydic florals fell out of fashion from the 1990s as fresher, fruitier styles took over, but aldehydes never disappeared. They give laundry and soap scents their crisp clean-linen character, and niche perfumers have revived them in retro-modern compositions that play on their metallic, waxy facets. Being cheap and potent, a fraction of a percent can change a formula.

How Aldehydes wears and what it pairs with

Aldehydes are most noticeable in the opening, where they give a burst of lift, but the heavier ones linger into the heart and help a fragrance radiate. They sit best with rose, jasmine, ylang-ylang, iris, neroli, powdery musks, sandalwood and vetiver, and in soft woody bases that let their soapy cleanliness last.