Stearin

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Stearin[1]
Skeletal formula of stearin
Powder of stearin
Identifiers
CAS number555-43-1 YesY
PubChem11146
ChemSpider10673 N
ChEBICHEBI:45956 N
Jmol-3D imagesImage 1
Properties
Molecular formulaC57H110O6
Molar mass891.48 g mol−1
AppearanceWhite powder
OdorOdorless
Density0.862 g/cm3 (80 °C)
0.8559 g/cm3 (90 °C)[2]
Melting point54–72.5 °C (129.2–162.5 °F; 327.1–345.6 K) [3]
Solubility in waterInsoluble
SolubilitySlightly soluble in C6H6, CCl4
Soluble in acetone, CHCl3
Insoluble in EtOH[2]
Refractive index (nD)1.4395 (80 °C)[2]
Structure
Crystal structureTriclinic (β-form)[4]
Space groupP1 (β-form)[4]
Lattice constanta = 12.0053 Å, b = 51.902 Å, c = 5.445 Å (β-form)[4]
Lattice constantα = 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
So298
1534.7 J/mol·K (liquid)[5]
Std enthalpy of
formation
ΔfHo298
−2344 kJ/mol[5]
Std enthalpy of
combustion
ΔcHo298
35806.7 kJ/mol[5]
Hazards
NFPA 704
Flash point≥ 300 °C (572 °F; 573 K)
closed cup[6]
LD502000 mg/kg (rats, oral)[6]
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references
 
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Stearin[1]
Skeletal formula of stearin
Powder of stearin
Identifiers
CAS number555-43-1 YesY
PubChem11146
ChemSpider10673 N
ChEBICHEBI:45956 N
Jmol-3D imagesImage 1
Properties
Molecular formulaC57H110O6
Molar mass891.48 g mol−1
AppearanceWhite powder
OdorOdorless
Density0.862 g/cm3 (80 °C)
0.8559 g/cm3 (90 °C)[2]
Melting point54–72.5 °C (129.2–162.5 °F; 327.1–345.6 K) [3]
Solubility in waterInsoluble
SolubilitySlightly soluble in C6H6, CCl4
Soluble in acetone, CHCl3
Insoluble in EtOH[2]
Refractive index (nD)1.4395 (80 °C)[2]
Structure
Crystal structureTriclinic (β-form)[4]
Space groupP1 (β-form)[4]
Lattice constanta = 12.0053 Å, b = 51.902 Å, c = 5.445 Å (β-form)[4]
Lattice constantα = 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
So298
1534.7 J/mol·K (liquid)[5]
Std enthalpy of
formation
ΔfHo298
−2344 kJ/mol[5]
Std enthalpy of
combustion
ΔcHo298
35806.7 kJ/mol[5]
Hazards
NFPA 704
Flash point≥ 300 °C (572 °F; 573 K)
closed cup[6]
LD502000 mg/kg (rats, oral)[6]
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
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.[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[edit]

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[edit]

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 C17H35COONa

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

See also[edit]

References[edit]

  1. ^ Merck Index, 11th Edition, 9669.
  2. ^ a b c 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. ^ a b c 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.  edit
  4. ^ a b c 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 Structural Science 57 (3): 372. doi:10.1107/S0108768100019121.  edit
  5. ^ a b c d 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. ^ a b c "MSDS of Stearin Wax". http://www.swna.us. Sasol Wax North America Corp. Retrieved 2014-06-19. 
  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".