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Undecylenic Acid


The pyrolysis of castor oil at 700oC under reduced pressure has been used to obtain heptaldeyde and undecylenic acid. (Pyrolysis is the chemical decomposition of organic materials by heating in the absence of oxygen or any other reagents, except possibly steam.) Heptaldehyde can be further hydrogenated to produce alcohol for use as a plasticizer.

Another method is via the hydrolysis of Methyl Undecylenate. Methyl Undecylenate is hydrolysed to give Undecylenic Acid.

(CH2=CH(CH2)8COOCH3) Methyl Undecylenate -> H2O -> Undecylenic Acid (CH2=CH (CH2)8COOH)


Synonyms: 10-Hendecenoic; 10-Henedecenoic acid; 10-Undecylenic acid; Undecyl-10-enic acid

CAS Number


Chemical Formula


Auto-Ignition Temperature

275C (527F)

Flash Points

Closed Cup: 148C (298.4F). Open Cup: 160C (320F)

Physical state and appearance

Solid (low melting point solid)


Fruity. Rosy

Molecular Weight

184.28 g/mole


Yellow. (Light.)

Boiling Point

232 [email protected] 182 mm Hg; 230 [email protected] 130 mm Hg.

Melting Point

24.5C (76.1F)

Specific Gravity

0.9072 (Water = 1)

Decomposition Temperature

275C (527F) @ 760 mm Hg



         Undecylenic acid has a long history as antifungal drug. It is used to treat some types of fungus infections.

         Undecylenic acid is a natural fungicide and is FDA approved in over-the-counter medications for skin disorders or problems. It is the active ingredient in medications for skin infections, and relieves itching, burning, and irritation. For example, it is used against fungal skin infections such as athlete's foot, ringworm, and Candida albicans. It is also used in the treatment of psoriasis.

         Undecylenic acid has been shown to be approximately six times more effective as an antifungal than caprylic acid, and is effective in maintaining a healthy balance of intestinal and vaginal flora.