Undecylenic acid is an eleven-carbon fatty acid with a double bond at the end of the chain. It is used as the starting point for polyamide 11, in antifungal skin and foot products, in cosmetics and fragrances, and in specialty polymers.
It is made by cracking castor oil, ricinoleic acid or methyl ricinoleate at very high temperature. The molecule breaks into undecylenic acid, or its methyl ester, and heptaldehyde. Both products are then purified by distillation.
Main uses
- Polyamide 11, a bio-based engineering plastic made via 11-aminoundecanoic acid and used in fuel lines, air brake tubing and sports goods.
- Antifungal products, where undecylenic acid and its zinc salt are used in creams, powders and sprays.
- Cosmetic ingredients, including surfactants and conditioning agents derived from it.
- Fragrance and flavour chemicals, made from undecylenic acid and from the heptaldehyde co-product.
- Silicone modifiers, lubricant additives and other specialty chemicals that use the terminal double bond.
What to check
Purity is the main point. Ask for the assay by gas chromatography, acid value, iodine value, colour and moisture. Ask also how much of the chain isomers and other fatty acids remain. For cosmetic and antifungal uses, ask about heavy metals and residual solvents too.
If the product goes into medicines or medical devices, your own market's pharmacopoeia and regulatory rules apply. That is a separate regulated supply chain, and you or your regulatory adviser must confirm what grade and documentation are required.
Undecylenic acid is a liquid that solidifies in a cool room, so it ships in drums and may need gentle warming to unload. Check section 14 of the safety data sheet for transport classification. Our guide on the safety data sheet explains what the SDS should contain.
Supply and lead times
Undecylenic acid comes from a demanding high-temperature process, and few plants run it. Supply is therefore narrower than for HCO or 12-HSA. Lead times can stretch when a plant runs a long campaign of another product on the same unit.
Ask how often the plant runs the cracking unit and whether it keeps stock between runs. If you need regular supply, share a forecast early so your volumes are planned into its campaigns.
Heptaldehyde, the co-product, has its own market in fragrance and flavour chemicals. A plant that sells both has a steadier business. This is another reason to ask what share of the plant's output goes to export and to which uses. For background on the castor chain, see what castor oil derivatives are made in Gujarat.
Documents to request
Ask for a current safety data sheet, a certificate of analysis for each lot and, for EU imports, confirmation of how REACH registration is handled. Read who is responsible for REACH registration before you assume it is covered.
Next step
Few plants make undecylenic acid, and many sellers are traders. We check who really makes it, test samples and supervise loading. Book a free sourcing review to discuss your grade.