Undecylenic aldehyde (Aldehyde C-11)

Origin

A synthetic unsaturated aldehyde with an eleven-carbon chain bearing a terminal double bond, produced industrially. It does not have a significant natural source in commercial terms.

The smell

A green, waxy aldehyde with a fresh, soapy and slightly metallic quality. It carries a cool, almost rosy-green facet that differs from the fattier C-10 and C-12. The effect is clean and diffusive, lending an airy, fizzy sparkle.

Key quality

Its terminal unsaturation gives it a greener, fresher character than the saturated aldehydes of similar chain length.

Historical use

It formed part of the aldehydic accord deployed in the 1921 launch of Chanel No. 5, one of the earliest fragrances built around a synthetic aldehyde overdose.