Everything about Stearic Acid totally explained
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Stearic acid (
IUPAC systematic name:
octadecanoic acid) is one of the useful types of saturated
fatty acids that come from many animal and vegetable fats and oils. It is a waxy solid, and its chemical formula is C
18H
36O
2. Its name comes from the
Greek word
stéar (
genitive:
stéatos), which means
tallow. The salts and
esters of stearic acid are called
stearates.
Production
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.
Uses
Stearic acid is useful as an ingredient in making
candles,
soaps,
plastics,
oil pastels and
cosmetics, and for softening
rubber. Stearic acid is used to harden soaps, particularly those made with vegetable oil.
Stearic acid is also used as a parting compound when making plaster castings from a plaster
piece mold or
waste mold and when making the mold from a shellacked clay original. In this use, powdered stearic acid is dissolved in water and the solution is brushed onto the surface to be parted after casting.
Esters of stearic acid with
ethylene glycol,
glycol stearate and
glycol distearate are used to produce a pearly effect in shampoos, soaps, and other cosmetic products. They are added to the product in molten form and allowed to crystalize under controlled conditions.
In
fireworks, stearic acid is often used to coat
metal powders such as
aluminium and
iron. This prevents
oxidation allowing compositions to be stored for longer.
It is used along with simple
sugar or
corn syrup as a
hardener in
candies.
Reactions
Stearic acid undergoes the typical reactions of saturated carboxylic acids, notably reduction to
stearyl alcohol, and esterification with a range of alcohols.
Metabolism
An
isotope labeling study in humans 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.
Further Information
Get more info on 'Stearic Acid'.
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