Elaidic acid
Structural formula | ||||||||||||||||||||||
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General | ||||||||||||||||||||||
Surname | Elaidic acid | |||||||||||||||||||||
other names |
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Molecular formula | C 18 H 34 O 2 | |||||||||||||||||||||
Brief description |
colorless scales |
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properties | ||||||||||||||||||||||
Molar mass | 282.45 g · mol -1 | |||||||||||||||||||||
Physical state |
firmly |
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density |
0.8734 g cm −3 (45 ° C) |
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Melting point |
44-45 ° C |
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boiling point |
288 ° C (133 hPa) |
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solubility |
almost insoluble in water |
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Refractive index |
1.4499 (45 ° C) |
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safety instructions | ||||||||||||||||||||||
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Toxicological data | ||||||||||||||||||||||
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 |
Elaidic acid (from Gr. Elaion , "oil") is a monounsaturated fatty acid . The molecule contains an unbranched chain of 18 carbon atoms with a single double bond in the middle . Since both parts of the chain are in a trans arrangement on the double bond, it is also referred to as a trans fatty acid .
The chemical formula is CH 3 - (CH 2 ) 7 –CH = CH– (CH 2 ) 7 –COOH, the systematic name trans -9-octadecenoic acid. The corresponding cis isomer , which occurs much more frequently in nature, is called oleic acid .
The elaidic acid forms colorless crystals of density 0.87 kg / l, melting at 44 to 45 ° C.
Fats (triester of glycerine ) with an elaidic acid residue can - undesirably - arise during fat hardening , but smaller proportions of such glycerides can also be found in milk fat , beef tallow and other fats from ruminants .
proof
The detection and determination of the content of elaidic acid is usually carried out by gas chromatography of the methyl ester; In addition, the unsaturated isomers can be separated using silver nitrate thin-layer chromatography .
Individual evidence
- ↑ a b c d Datasheet Elaidic acid, 98% from AlfaAesar, accessed December 7, 2019 ( PDF )(JavaScript required) .
- ↑ a b c David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 96th edition. (Internet version:), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-240.
- ↑ a b data sheet elaidic acid from Sigma-Aldrich , accessed on April 14, 2010 ( PDF ).
- ↑ B. Breuer, T. Stuhlfauth, HP Fock: Separation of fatty acids or methyl esters including positional and geometric isomers by alumina thin-layer chromatography. In: J. of Chromatogr. Science. 25 (7), 1987, pp. 302-306, PMID 3611285 .