|Jmol-3D images||Image 1|
|Molar mass||891.48 g/mol|
|Density||0.862 g/cm3 at 80 °C|
|Melting point||55 °C (131 °F; 328 K)|
|Solubility in water||Insoluble|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Stearin //, 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. Like other triglycerides, stearin can crystallise in three polymorphs. For stearin, these melt at 54.5, 65, and 73 °C.
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.
It is used as a hardening agent 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.