View source for Stearin

{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 429325307
| Reference = <ref>''[[Merck Index]]'', 11th Edition, '''9669'''.</ref>
| ImageFile = stearin.png
| ImageSize = 250px
| ImageClass = skin-invert
| ImageAlt = Skeletal formula of stearin
| ImageFile1 = Tristearin 3D spacefill.png
| ImageAlt1 = Space-filling model of the tristearin molecule
| ImageFile2 = Stearin krystalický.JPG
| ImageAlt2 = Powder of stearin
| SystematicName = Propane-1,2,3-triyl tri(octadecanoate)
| OtherNames = Tristearin; Trioctadecanoin; Glycerol tristearate; Glyceryl tristearate
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 555-43-1
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = P6OCJ2551R
| PubChem = 11146
| ChEBI_Ref = {{ebicite|changed|EBI}}
| ChEBI = 45956
| SMILES = CCCCCCCCCCCCCCCCCC(=O)OCC(COC(=O)CCCCCCCCCCCCCCCCC)OC(=O)CCCCCCCCCCCCCCCCC
| 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
| InChIKey = DCXXMTOCNZCJGO-UHFFFAOYSA-N
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 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
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = DCXXMTOCNZCJGO-UHFFFAOYSA-N
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID = 10673
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = D10637 
 }}
|Section2={{Chembox Properties
| C=57 | H=110 | O=6
| Appearance = White powder
| Odor = Odorless
| Density = 0.862 g/cm<sup>3</sup> (80 °C)<br> 0.8559 g/cm<sup>3</sup> (90 °C)<ref name=crc>{{CRC90}}</ref>
| MeltingPtC = 54-72.5
| MeltingPt_ref = <ref name=spring />
| Solubility = Insoluble
| SolubleOther = Slightly soluble in [[benzene|C<sub>6</sub>H<sub>6</sub>]], [[carbon tetrachloride|CCl<sub>4</sub>]]<br> Soluble in [[acetone]], [[chloroform|CHCl<sub>3</sub>]]<br> Insoluble in [[ethanol|EtOH]]<ref name=crc />
| RefractIndex = 1.4395 (80 °C)<ref name=crc />
  }}
|Section4={{Chembox Thermochemistry
| Entropy = 1534.7 J/mol·K (liquid)<ref name=nist>{{nist|name=Tristearin|id=C555431|accessdate=2014-06-19|mask=FFFF|units=SI}}</ref>
| DeltaHc = 35806.7 kJ/mol<ref name=nist />
| DeltaHf = −2344 kJ/mol<ref name=nist />
| HeatCapacity = 1342.8 J/mol·K (β-form, 272.1&nbsp;K)<br> 1969.4 J/mol·K (346.5 K)<ref name=spring /><ref name=nist />
  }}
|Section3={{Chembox Structure
| CrystalStruct = [[triclinic crystal system|Triclinic]] (β-form)<ref name=iucr>{{Cite journal | doi = 10.1107/S0108768100019121| title = Structure of β-trimyristin and β-tristearin from high-resolution X-ray powder diffraction data| journal = Acta Crystallographica Section B| volume = 57| issue = 3| pages = 372–377| year = 2001| last1 = Van Langevelde | first1 = A. | last2 = Peschar | first2 = R. | last3 = Schenk | first3 = H. | doi-access = | pmid = 11373397}}</ref>
| SpaceGroup = P{{overline|1}} (β-form)<ref name=iucr />
| PointGroup = 
| LattConst_a = 12.0053&nbsp;Å
| LattConst_b = 51.902&nbsp;Å
| LattConst_c = 5.445&nbsp;Å (β-form)<ref name=iucr />
| LattConst_alpha = 73.752
| LattConst_beta = 100.256
| LattConst_gamma = 117.691
  }}
|Section7={{Chembox Hazards
| FlashPtC = 300
| FlashPt = ≥
| FlashPt_notes = closed cup<ref name=swan />
| AutoignitionPtC = 
| NFPA-H = 1
| NFPA-F = 1
| NFPA-R = 0
| NFPA_ref = <ref name=swan>{{cite web|url = http://www.swna.us/MSDS/Stearin%20Wax%20MSDS.pdf|title = MSDS of Stearin Wax|website = www.swna.us|accessdate = 2014-06-19|publisher = Sasol Wax North America Corp.|archive-date = 2016-03-04|archive-url = https://web.archive.org/web/20160304043537/http://www.swna.us/MSDS/Stearin%20Wax%20MSDS.pdf|url-status = dead}}</ref>
| LD50 = 2000 mg/kg (rats, oral)<ref name=swan />
  }}
}}

'''Stearin''' {{IPAc-en|ˈ|s|t|ɪər|ᵻ|n}}, or '''tristearin''', or '''glyceryl tristearate''' is an odourless, white powder. It is a [[triglyceride]] derived from three units of [[stearic acid]].  Most triglycerides are derived from at least two and more commonly three different [[fatty acid]]s.<ref name=Ullmann>{{cite encyclopedia |author=Alfred Thomas |encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry |publisher=Wiley-VCH |place=Weinheim |year=2002 |doi=10.1002/14356007.a10_173 |chapter=Fats and Fatty Oils |isbn=978-3527306732}}</ref>  Like other triglycerides, stearin can crystallise in three [[Polymorphism (materials science)|polymorphs]].  For stearin, these melt at 54 (α-form), 65, and {{nowrap|72.5 °C}} (β-form).<ref name=spring>{{Cite journal | doi = 10.1007/BF02643296| title = Thermal properties of fats and oils| journal = Journal of the American Oil Chemists' Society| volume = 24| issue = 5| pages = 140| year = 1947| last1 = Charbonnet | first1 = G. H. | last2 = Singleton | first2 = W. S.| s2cid = 101805872}}</ref>

Note that '''stearin''' is also used to mean the solid component of an oil or fat that can be separated into components that melt at higher (the stearin) and lower (the olein) temperatures. This is the usage meant in an example such as [[palm stearin]].

== Occurrence ==
Stearin is obtained from animal [[fat]]s 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 {{nowrap|−5 °C}}.

== Uses ==
Stearin is used as a hardening agent in the manufacture of [[candle]]s and [[soap]].<ref>{{cite journal|title= Waxes in the candle industry | doi=10.1007/BF02636720 | volume=12|issue= 11 |journal=Oil & Soap|pages=263–265 | last1 = Geller | first1 = L. W.|year= 1935 | s2cid=97117097 }}</ref>  It is mixed with a [[sodium hydroxide]] solution in water, creating a  reaction which gives [[glycerin]] and [[sodium stearate]], the main ingredient in most soap:

:C<sub>3</sub>H<sub>5</sub>(C<sub>18</sub>H<sub>35</sub>O<sub>2</sub>)<sub>3</sub> + 3 NaOH → C<sub>3</sub>H<sub>5</sub>(OH)<sub>3</sub> + 3 C<sub>18</sub>H<sub>35</sub>OONa

Stearin is also added to aluminium flakes to help in the grinding process in making dark aluminium powder.{{what|What is "dark aluminum powder"?|date=May 2021}}

==See also==
*[[Candle]]
*[[Michel Eugène Chevreul]]
*[[Soap making]]
*[[Stearic acid]]

== References ==
{{reflist}}

{{glycerides}}

[[Category:Animal fat products]]
[[Category:Triglycerides]]
[[Category:Stearate esters]]