Stearic acid
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| Stearic acid | |
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| Chemical name | Octadecanoic acid |
| Other names | Stearic acid |
| Chemical formula | C18H36O2 |
| Molar mass | 284.47 g/mol |
| CAS number | [57-11-4] |
| Density | 0.847 g/cm3 at 70 °C |
| Melting point | 69-70 °C |
| Boiling point | 383 °C |
| Acid value | 200-210 mg KOH/g |
| SMILES | CCCCCCCCCCCCCCCCCC(=O)O |
| Disclaimer and references | |
Stearic acid (IUPAC systematic name: 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, particularly 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.
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[edit] Metabolism
An isotope labeling study[1] concluded that the fraction of dietary stearic acid oxidatively desaturated to oleic acid was 2.4 times higher than the fraction of palmitic acid analogously converted to palmitoleic acid. Also, stearic acid was less likely to be incorporated into cholesterol esters. These findings may indicate that stearic acid is less unhealthy than other saturated fatty acids.
[edit] See also
[edit] References
- ^ Emken, Edward A. (1994). "Metabolism of dietary stearic acid relative to other fatty acids in human subjects" (PDF). American Journal of Clinical Nutrition 60: 1023S–1028S. Retrieved on 2006-08-07.
- Merck Index, 11th Edition, 8761.
