Undecylenic Acid is an unsaturated carboxylic acid. The molecules of most natural fatty acids have an even number of carbon chains due to the linkage together by ester units. Analogous compounds of odd numbers carbon chain fatty acids are supplemented synthetically. Pelargonic acid, C-9 odd numbers carbon chain fatty acid, is relatively high cost fatty acid. Pelargonic acid can be prepared by o zonolysis which uses ozone is to cleave the alkene bonds. Eexample of ozonolysis in commerce is the production of odd carbon number carboxylic acids such as azelaic acid and pelargonic acid and simple carboxylic acids such as formic acid and oxalic acid. When ricinoleic acid, an u nsaturated fatty acid containing one -OH group, derived from castor oil, is pyrolyzed by heating in the absence of air, it breaks down to give undecylenic acid and n-heptaldehyde. This product has the bifunctionality, odd carbon number and the position of its unsaturated double bond at the end of the chain, makes it a versatile tool for chemical synthesis. It's anti-fungal properties are useful in cosmetics and pharmaceuticals. Undecylenic Acid and its aldehyde are used to formulate perfumes. Undecylenic acid and its zinc salt are used for the treatment and prevention of superficial fungus infections of the skin, primarily tinea pedis as well as relieves itching, burning and irritation.
Alkalinity : Mix g with 5 ml of ethanol (96 per cent) and ml of phenol red solution. Add 50 ml of carbon dioxide-free water and examine immediately. No reddish colour appears.
Alkali and alkaline-earth metals : Maximum per cent.
To g add 25 ml of water and 5 ml of hydrochloric acid and heat to boiling. Filter whilst hot. Wash the filter and the residue with 25 ml of hot water. Combine the filtrate and washings and add concentrated ammonia until alkaline. Add ml of thioacetamide solution and heat on a water-bath for 30 min. Filter and wash the precipitate with 2 quantities, each of 10 ml, of water. Combine the filtrate and washings, evaporate to dryness on a water-bath and ignite. The residue weighs a maximum of 20 mg.
Sulphates : Maximum 500 ppm.
Loss on drying : Maximum per cent, determined on g by drying in an oven at 105C.
Degree of un-saturation : Dissolve g in a mixture of 5 ml of dilute hydrochloric acid R and 30 ml of glacial acetic acid. Using ml indigo carmine solution, added towards the end of the titration as indicator. Titrate with M bromide-bromate until the colour changes from blue to yellow.
ml to ml of M bromide-bromate is required. Carry out a blank titration.