Aldehyde C-11 undecylenic

Say itAL-dih-hyde SEE-ih-LEV-un un-des-ih-LEN-ik

Waxy, green-rosy aldehyde with orange peel and a clean, soapy sparkle.

What it is: A molecule made in a lab.
When you smell it: Top notes: the first minutes.
What perfumers do with it: Gives the green, rosy aldehydic glow to florals, violets, chypres and tuberose; stable in detergents.
Worth knowing: 'Aldehyde C-14' (peach) and 'C-16' (strawberry) are not aldehydes at all; the old trade names simply stuck.
Known in: Chanel No. 5 (Chanel, 1921)
Also called: 10-undecenal; undecylenic aldehyde

Not on the label of any of the 232 perfumes read so far.

Sources