Database/Perfuming/Undecenal
Route-dependent · ISO 16128

Is Undecenal natural?

It depends. The C11 unsaturated aldehyde used in perfumery is sold both as the castor-oil-derived 10-isomer and as synthetic 2-undecenal, and the INCI name covers both, so the score is route- and isomer-dependent. Consistent with Undecylenic Acid (1.0) and Nonanal (route-dependent).

INCI nameUndecenal
CAS1337-83-3
FunctionPerfuming
FeedstockEither castor-oil undecylenic acid oxidised to the aldehyde,…

Why the score varies

This ingredient is made commercially by more than one route, and ISO 16128 scores the feedstock actually used. Without a supplier certificate of origin the value cannot be claimed.

RouteFeedstockNOIShareNotes
castor-derived 10-undecenalundecylenic acid / undecylenyl alcohol from castor-oil ricinoleate pyrolysis, oxidised to the aldehyde1.00All eleven carbons are castor-oil carbons (aldehyde C-11 undecylenic grade).
2-undecenal from oleochemical nonanalnonanal from oleic-acid ozonolysis, aldol-condensed with petrochemical acetaldehyde0.74Nonanal-derived C9H17 125.2/168.3 = 0.74 natural; the C2H3O from acetaldehyde is petrochemical.
fully petrochemical aldoloxo-process nonanal plus acetaldehyde0.00No natural carbon.
Ask your supplier. A batch-specific certificate of origin or bio-based carbon test (ASTM D6866) settles which route applies.

How we scored it

C11H20O 168.3 Da. INCI Undecenal (CAS 1337-83-3) does not fix the double-bond position: castor-derived 10-undecenal is fully natural (1.00); 2-undecenal made by aldol condensation keeps 125.2 Da of nonanal-derived carbon, natural only if the nonanal came from oleic-acid ozonolysis (0.74), and is 0.00 from oxo nonanal. Headline shows the best commercial route.
What counts. ISO 16128-2 scores the atoms that remain in the final ingredient. Reagents, solvents, catalysts and protecting groups used during manufacture leave no mass behind and are not counted.

Where it comes from

Either castor-oil undecylenic acid oxidised to the aldehyde, or nonanal condensed with acetaldehyde.

In plain English

A fragrance ingredient with a fresh, fatty-green smell. It's mostly made through industrial chemical synthesis, though trace amounts occur naturally in some plant oils.

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References

  1. 1ISO 16128-1:2016 and ISO 16128-2:2017 — Guidelines on technical definitions and criteria for natural and organic cosmetic ingredients and products. ISO, Geneva.
  2. 2UNDECENAL. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
  3. 3UNDECENAL. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=UNDECENAL