Stearic acid
Encyclopedia : S : ST : STE : Stearic acid
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| Chemical name | |
| Other names | Stearic acid |
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| Density | 3 at 70 °C |
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| Acid value | KOH/g
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Stearic acid, also called octadecanoic acid, is one of the useful types of saturated fatty acids that comes from many animal and vegetable fats and oils. It is a waxy solid, and its chemical formula is CH3(CH2)16COOH. Its name comes from the Greek word stear, which means tallow. The term stearate is applied to the salts and esters of stearic acid.
Stearic acid is prepared by treating animal fat with water at a high pressure and temperature, leading to the hydrolysis of triglycerides. It can also be obtained from the hydrogenation of some unsaturated vegetable oils. Common stearic acid is actually a mix of stearic acid and palmitic acid, although purified stearic acid is available separately.
Stearic acid is useful as an ingredient in making candles, soaps, plastics, oil pastel, cosmetics and for softening rubber. Stearic acid is used to harden soaps, particulary those made with vegetable oil, that otherwise tend to be very soft.
Stearic acid is also useful as a parting compound when making plaster castings from a plaster piece mold or waste mold and when making the mold from a shellaced clay original. In this use, powdered stearic acid is dissolved in water and the solution brushed upon the surface to be parted after casting.
Reduction of stearic acid yields stearyl alcohol.
See also
References
- Merck Index, 11th Edition, 8761.
External links
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