Acidum Oleicum, B.P. Oleic Acid.
Related entry: Stearic acid
C19H34O2 = 282.272.
Oleic acid, C17H33COOH, is obtained by the saponification of oils with alkalies, the soap formed is then decomposed with hydrochloric or sulphuric acid, and the fatty acid thus liberated; or by treating fats with superheated steam. It is also official in the U.S.P., and is there stated to be prepared in a sufficiently pure condition by cooling commercial oleic acid to about 5°, then separating and preserving the liquid portion. It occurs as a yellowish or brownish-yellow liquid with a peculiar tallow-like odour and taste, and a slight acid reaction. It becomes semi-solid when cooled to 4.5° to 5°, melting again at 13.3° to 15.5°. Specific gravity, 0.890 to 0.910 (about 0.895 at 25°). The acid should be free from more than traces of stearic or palmitic acid, but usually contains traces of iron, probably derived from the vessels in which it is stored. The oleic acid of commerce will not comply with the B.P. tests.
Insoluble in water; readily soluble in alcohol, chloroform, or ether.
Action and Uses.—Oleic acid is employed externally as an emollient, but its principal use is in the preparation of the metallic oleates and as an alkaloidal solvent. It has been administered as a substitute for olive oil, and prescribed for internal use in capsules containing 1 mil (15 minims) as a remedy for gall-stones (see Oleum Olivae).
Dose.—5 to 10 decimils (= 0.5 to 1 milliliters) (7 ½ to 15 minims).