Tristearin

Structural formula
General
Surname	Tristearin
other names	Trioctadecanoin Tristearoyl glycerol Glycerol tristearate 1,3-di (octadecanoyloxy) propan-2-yl-octadecanoate ( IUPAC )
Molecular formula	C 57 H 110 O 6
Brief description	white solid
External identifiers / databases
CAS number 555-43-1 EC number 209-097-6 ECHA InfoCard 100.008.271 PubChem 11146 Wikidata Q425640
properties
Molar mass	891.48 g mol −1
Physical state	firmly
density	1.058 g cm −3 (β shape) 0.86 g cm −3 (melt at 90 ° C)
Melting point	54 ° C (α – form) 72 ° C (β-form)
solubility	almost insoluble in water slightly soluble in cold alcohol easily soluble in benzene and chloroform
Refractive index	1.4395 (80 ° C)
safety instructions
GHS labeling of hazardous substances no GHS pictograms H and P phrases H: no H-phrases P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Tristearin is a chemical compound from the group of the simple triglycerides , whereby all three hydroxyl groups of the glycerin are esterified with the stearic acid .

Occurrence and extraction

Tristearin is the main component in sebum or kidney tallow from pork fat and can be extracted from it. In contrast, mono- and distearin are produced artificially. The preparation of the pure tristearin can take place by the catalytic hydrogenation of the unsaturated triglyceride trilinolein in n- hexane as solvent.

properties

Tristearin is a crystalline solid that can appear in three polymorphic forms. The α – form melts at 54 ° C with a melting enthalpy of 145 kJ · mol ⁻¹ . The melting point of the β – form is 72 ° C, and the enthalpy of fusion is 203 kJ · mol ⁻¹ . A β'-form that can be produced as an intermediate has a melting point of 63.5 C and a melting enthalpy of 143 kJ mol ⁻¹ . The forms α and β 'are monotropic to form β. The β-form is the thermodynamically stable form. The α – shape forms a hexagonal crystal lattice, where the parallel hydrocarbon chains are arranged perpendicular to the base plane. In the β form, the hydrocarbon groups are tilted to the base plane in a triclinic crystal lattice . The arrangement of the hydrocarbon chains in the β 'form corresponds to the β form, but an orthorhombic crystal lattice is formed. The connection is hardly volatile. The vapor pressures are in the temperature range of 253 ° C and 313 ° C between 1.3 · 10 ⁻³  mbar and 9.1 · 10 ⁻²  mbar. The vapor pressure function results according to August according to log ₁₀ (P) = −A / T + B (P in mmHg, T in K) with A = 8750 and B = 16.60. The enthalpy of vaporization is 167 kJ mol ⁻¹ . The enthalpy of combustion of the solid is −35.807 kJ mol ⁻¹ .

use

The ester is also used as a formulation aid in medicines, as an emulsifier and crystallization aid in food , as a plasticizer , lubricant and in cosmetics . In the USA , tristearin has GRAS status ( Generally Recognized As Safe ) and is added in amounts of up to 3% to various foods.

Individual evidence

1. ↑ ^{a b c} data sheet Glyceryl tristearate from Sigma-Aldrich , accessed on June 15, 2011 ( PDF ).
2. ^ D. Johansson, B. Bergenstahl: Sintering of fat crystal networks in oil during post-crystallization processes. In: J Am Oil Chem Soc . 72, 1995, pp. 911-920. doi: 10.1007 / BF02542069
3. ↑ Entry on tristearin in the hazardous substance database in "CLAKS" at the University of Hamburg
4. ↑ ^{a b c d} G. H. Charbonnet, WS Singleton: Thermal properties of fats and oils. VI. Heat capacity, heats of fusion and transition, and entropy of trilaurin, trimyristin, tripalmitin, and tristearin. In: J. Am. Oil Chem. Soc. 24, 1947, pp. 140-142. doi: 10.1007 / BF02643296
5. ↑ ES Domalski, ED Hearing: Heat Capacities and Entropies of Organic Compounds in the Condensed phase. Volume III. (= J. Phys. Chem. Ref. Data. 25). American Chemical Society, 1996, OCLC 68546879 . doi: 10.1063 / 1.555985
6. ↑ ^{a b c} Entry on glycerol tristearate. In: Römpp Online . Georg Thieme Verlag, accessed on June 19, 2014.
7. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-268.
8. ^ DW Rogers, DN Choudhury: Heats of hydrogenation of large molecules. Part 3 - Five simple unsaturated triglycerides (triacylglycerols). In: J. Chem. Soc. Faraday Trans. 1, 74, 1978, pp. 2868-2872.
9. ^ ES Lutton: The Polymorphism of Tristearin and Some of its Homologs. In: J. Am. Chem. Soc. 67, 1945, pp. 524-527. doi: 10.1021 / ja01220a008
10. ↑ ^{a b} M. Ollivon, R. Perron: Measurements of enthalpies and entropies of unstable crystalline forms of saturated even monoacid triglycerides. In: Thermochim. Acta. 53, 1982, pp. 183-194. doi: 10.1016 / 0040-6031 (82) 85007-7
11. ^ ES Lutton: Lipid structures. In: J. Am. Oil Chem. Soc. 49, 1972, pp. 1-9. doi: 10.1007 / BF02545128
12. ↑ ^{a b c} E. S. Perry, WH Weber, BF Daubert: Vapor Pressures of Phlegmatic Liquids. I. Simple and Mixed Triglycerides. In: J. Am. Chem. Soc. 71, 1949, pp. 3720-3726. doi: 10.1021 / ja01179a038
13. ↑ B. Freedman, MO Bagby, H. Khoury: Correlation of heats of combustion with empirical formulas for fatty alcohols. In: J. Am. Oil Chem. Soc. 66, 1989, pp. 595-596. doi: 10.1007 / BF02885455
14. ↑ George A. Burdock: Encyclopedia of food and color additives. CRC Press, 1997, ISBN 0-8493-9416-3 , pp. 1231-1232.