oleic acid is a monounsaturated omega-9 fatty acid that exists in animals and plants. pure oleic acid is a colorless oily liquid.
the physical and chemical properties of oleic acid are as follows:
oleic acid, together with other fatty acids, exists in the form of glycerides in all animal and vegetable oils and fats. in animal fats, oleic acid accounts for about 40% to 50% of fatty acids. the changes in vegetable oils are greater, reaching 83% in camellia oil, 54% in peanut oil, and only 5% to 6% in coconut oil.
pure oleic acid is a colorless oily liquid with the smell of animal oil or vegetable oil. the color gradually becomes darker after being left in the air for a long time. industrial products are yellow to red oily liquid with the smell of lard. the melting point is 16.3°c, the boiling point is 286°c (100 mmhg), the relative density is 0.8935 (20/4°c), the refractive index is 1.4582, and the flash point is 372°c. easily soluble in ethanol, ether, chloroform and other organic solvents, but insoluble in water. flammable. it is easily saponified when exposed to alkali and forms a white soft solid after solidification. easily oxidized, polymerized or decomposed under high heat. non-toxic.
when oleic acid reacts with nitric acid, it will be isomerized into the trans isomer. the melting point of elaidic acid is 44-45℃; hydrogenation will give stearic acid; oxidation with potassium permanganate will give it a mixture of n-nonanoic acid and azelaic acid. because oleic acid contains double bonds, it can undergo auto-oxidation when left in the air for a long time, and locally transform into carbonyl-containing substances with a putrid smell, which is the reason for the deterioration of oil. commercial oleic acid generally contains 7% to 12% saturated fatty acids, such as palmitic acid and stearic acid.
