Stearin

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Stearin[1]
IUPAC name

1,3-Di(octadecanoyloxy)propan-2-yl octadecanoate

Other names

Tristearin; Trioctadecanoin; Glycerol tristearate; Glyceryl tristearate

Identifiers
CAS number 555-43-1 YesY
PubChem 11146
Jmol-3D images Image 1
Properties
Molecular formula C57H110O6
Molar mass 891.48 g/mol
Appearance White powder
Density 0.862 g/cm3 at 80 °C
Melting point 55 °C; 131 °F; 328 K
Solubility in water Insoluble
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Stearin /ˈstɪərɨn/, or tristearin, or glyceryl tristearate is a triglyceride derived from three units of stearic acid. Most triglycerides are derived from at least two and more commonly three different fatty acids.[2] Like other triglycerides, stearin can crystallise in three polymorphs. For stearin, these melt at 54.5, 65, and 73 °C.

Occurrence

Stearin is obtained from animal fats created as a byproduct of processing beef. It can also be found in tropical plants such as palm. It can be partially purified by "dry fractionation" by pressing tallow or other fatty mixtures, leading to separation of the higher melting stearin-rich material from the liquid, which is typically enriched in fats derived from oleic acid. It can be obtained by "interesterification", again exploiting its higher melting point which allows the higher melting tristearin to be removed from the equilibrated mixture. Stearin is a side product obtained during the extraction of cod liver oil removed during the chilling process at temperatures below −5 °C.

Uses

It is used as a hardening agent[3] in the manufacture of candles and soap. In the manufacture of soap, stearin is mixed with a sodium hydroxide solution in water. The following reaction gives glycerin and sodium stearate, the main ingredient in most soap:

C3H5(C18H35O2)3 + 3 NaOH → C3H5(OH)3 + 3 C17H35COONa

Stearin is also used in conjunction with aluminium flakes to help in the grinding process in making dark aluminium powder.

See also

References

  1. ↑ Merck Index, 11th Edition, 9669.
  2. ↑ Alfred Thomas (2002). Fats and Fatty Oils. "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a10_173. ISBN 3527306730. 
  3. ↑ "Waxes in the candle industry". 
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