Glycerol ester

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Glycerin esters are esters that contain glycerin . Esters are made from an alcohol and a carboxylic acid. In glycerine esters, the alcohol is glycerine.

Example of a triglyceride in fats and oils. The fatty acid residue marked blue is saturated, the green marked is single, the red marked triple unsaturated . The double bonds are cis -configured. The triple acylated glycerine can be seen in black in the center . Oils contain a higher proportion of essential fatty acid residues (= unsaturated fatty acid residues) than fats.

The acid can be a carboxylic acid . This results in esters like those found in the typical representatives of animal and vegetable oils and fats .

The acid can also be a mineral acid (e.g. nitric acid ). A typical representative of such esters is “nitroglycerin”, which is correctly called glycerol trinitrate .

In the case of glycerol esters, a distinction is made between mono-, di- and triesters depending on the number of alcohol molecules esterified with the glycerol molecule. Phospholipids such as phosphatidylcholines are usually esterified with a substituted or unsubstituted phosphoric acid and one or two fatty acids.

The reaction of alcohols and acids to form esters is called esterification . Since one water molecule is formed per ester bond during the reaction, esterification belongs to the type of condensation reaction . Small amounts of strong mineral acids (usually sulfuric acid ) serve as catalysts . The esterification is subject to chemical equilibrium , so the ester yield increases when water is removed from the reaction mixture.

use

Glycerine ester (usually obtained from the root resin of conifers by steam distillation ) is mainly used to stabilize the appearance and color of non-alcoholic beverages. So far, no harmful side effects are known.

Glycerine esters from root resin are approved in the EU as food additives with the designation E 445 .

Nitroglycerin is used as a drug and as an explosive .

See also

Individual evidence

  1. ^ Siegfried Hauptmann : Organic Chemistry , 2nd revised edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, pp. 653–654, ISBN 3-342-00280-8 .