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Tristearin

Stearin
Skeletal formula of stearin
Space-filling model of the tristearin molecule
Powder of stearin
Names
IUPAC name
1,3-Di(octadecanoyloxy)propan-2-yl octadecanoate
Other names
Tristearin; Trioctadecanoin; Glycerol tristearate; Glyceryl tristearate
Identifiers
555-43-1 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:45956 N
ChemSpider 10673 N
ECHA InfoCard 100.008.271
PubChem 11146
Properties
C57H110O6
Molar mass 891.50 g·mol−1
Appearance White powder
Odor Odorless
Density 0.862 g/cm3 (80 °C)
0.8559 g/cm3 (90 °C)
Melting point 54–72.5 °C (129.2–162.5 °F; 327.1–345.6 K)
Insoluble
Solubility Slightly soluble in C6H6, CCl4
Soluble in acetone, CHCl3
Insoluble in EtOH
1.4395 (80 °C)
Structure
Triclinic (β-form)
P1 (β-form)
a = 12.0053 Å, b = 51.902 Å, c = 5.445 Å (β-form)
α = 73.752°, β = 100.256°, γ = 117.691°
Thermochemistry
1342.8 J/mol·K (β-form, 272.1 K)
1969.4 J/mol·K (346.5 K)
1534.7 J/mol·K (liquid)
−2344 kJ/mol
35806.7 kJ/mol
Hazards
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point ≥ 300 °C (572 °F; 573 K) closed cup
Lethal dose or concentration (LD, LC):
LD50 (median dose)
2000 mg/kg (rats, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Stearin /ˈstɪərn/, 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 (α-form), 65, and 72.5 °C (β-form).

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:

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


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