Stearin

Stearin^[1]

Names
IUPAC name 1,3-Di(octadecanoyloxy)propan-2-yl octadecanoate
Other names Tristearin; Trioctadecanoin; Glycerol tristearate; Glyceryl tristearate
Identifiers
CAS Number	555-43-1
3D model (Jmol)	Interactive image
ChEBI	CHEBI:45956
ChemSpider	10673
ECHA InfoCard	100.008.271
PubChem	11146
InChI InChI=1S/C57H110O6/c1-4-7-10-13-16-19-22-25-28-31-34-37-40-43-46-49-55(58)61-52-54(63-57(60)51-48-45-42-39-36-33-30-27-24-21-18-15-12-9-6-3)53-62-56(59)50-47-44-41-38-35-32-29-26-23-20-17-14-11-8-5-2/h54H,4-53H2,1-3H3 Key: DCXXMTOCNZCJGO-UHFFFAOYSA-N InChI=1S/C57H110O6/c1-4-7-10-13-16-19-22-25-28-31-34-37-40-43-46-49-55(58)61-52-54(63-57(60)51-48-45-42-39-36-33-30-27-24-21-18-15-12-9-6-3)53-62-56(59)50-47-44-41-38-35-32-29-26-23-20-17-14-11-8-5-2/h54H,4-53H2,1-3H3 Key: DCXXMTOCNZCJGO-UHFFFAOYSA-N
SMILES CCCCCCCCCCCCCCCCCC(=O)OCC(COC(=O)CCCCCCCCCCCCCCCCC)OC(=O)CCCCCCCCCCCCCCCCC
Properties
Chemical formula	C57H110O6
Molar mass	891.50 g·mol^−1
Appearance	White powder
Odor	Odorless
Density	0.862 g/cm^3 (80 °C) 0.8559 g/cm^3 (90 °C)[2]
Melting point	54–72.5 °C (129.2–162.5 °F; 327.1–345.6 K) [3]
Solubility in water	Insoluble
Solubility	Slightly soluble in C6H6, CCl4 Soluble in acetone, CHCl3 Insoluble in EtOH[2]
Refractive index (nD)	1.4395 (80 °C)[2]
Structure
Crystal structure	Triclinic (β-form)[4]
Space group	P1 (β-form)[4]
Lattice constant	a = 12.0053 Å, b = 51.902 Å, c = 5.445 Å (β-form)[4] α = 73.752°, β = 100.256°, γ = 117.691°
Thermochemistry
Specific heat capacity (C)	1342.8 J/mol·K (β-form, 272.1 K) 1969.4 J/mol·K (346.5 K)[3][5]
Std molar entropy (S^o298)	1534.7 J/mol·K (liquid)[5]
Std enthalpy of formation (ΔfH^o298)	−2344 kJ/mol[5]
Std enthalpy of combustion (ΔcH^o298)	35806.7 kJ/mol[5]
Hazards
NFPA 704	[6] 1 1 0
Flash point	≥ 300 °C (572 °F; 573 K) closed cup[6]
Lethal dose or concentration (LD, LC):
LD50 (median dose)	2000 mg/kg (rats, oral)[6]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Stearin /ˈstɪərᵻn/, 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.^[7] Like other triglycerides, stearin can crystallise in three polymorphs. For stearin, these melt at 54 (α-form), 65, and 72.5 °C (β-form).^[3]

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^[8] 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 C₁₈H₃₅COONa

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

See also

• Michel Eugène Chevreul
• Soap making
• Stearic acid
• Candle

References

1. Merck Index, 11th Edition, 9669.
2. Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0.
3. Charbonnet, G. H.; Singleton, W. S. (1947). "Thermal properties of fats and oils". Journal of the American Oil Chemists Society. 24 (5): 140. doi:10.1007/BF02643296.
4. Van Langevelde, A.; Peschar, R.; Schenk, H. (2001). "Structure of β-trimyristin and β-tristearin from high-resolution X-ray powder diffraction data". Acta Crystallographica Section B. 57 (3): 372. doi:10.1107/S0108768100019121.
5. Tristearin in Linstrom, P.J.; Mallard, W.G. (eds.) NIST Chemistry WebBook, NIST Standard Reference Database Number 69. National Institute of Standards and Technology, Gaithersburg MD. http://webbook.nist.gov (retrieved 2014-06-19)
6. "MSDS of Stearin Wax" (PDF). http://www.swna.us. Sasol Wax North America Corp. Retrieved 2014-06-19. External link in |website= (help)
7. 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.
8. "Waxes in the candle industry".