Decarboxylation
As decarboxylation refers to a chemical reaction , from a in the molecule a carbon dioxide molecule is cleaved. Decarboxylation can be carried out particularly easily in the case of carboxylic acids (preferably: β - keto acids or malonic acids ) by heating or by enzymatic catalysis . A six-membered transition state occurs.
With rapid heating of orsellinic occurs at 176 ° C Orcin .
A central decarboxylation in the primary metabolism of all living things is the oxidative decarboxylation of pyruvate or α-ketoglutarate . The former is the product that is formed at the end of glycolysis when glucose is broken down. With the help of many coenzymes, a multi-enzyme complex shortens the substrates by one carbon atom. Since two electrons are simultaneously transferred to a cellular hydrogen acceptor via FAD on NAD + , this subsequent oxidation is also referred to as oxidative decarboxylation.
α - Amino acids can be decarboxylated by heating in tetraethylene glycol dimethyl ether (TGDE) in the presence of catalytic amounts of cyclohexenone . Example: The decarboxylation of (2 S , 4 R ) 4-hydroxyproline produces ( R ) -3-hydroxypyrrolidine:
The biogenic amines are also formed in the metabolism through decarboxylation reactions.
See also
- Barton decarboxylation
- Carboxylation
- Decarboxylase
- Halodecarboxylation
- Hunsdiecker reaction
- Kemp decarboxylation
- Krapcho decarboxylation
- oxidative decarboxylation
- Decarbonylation
Individual evidence
- ^ Siegfried Hauptmann : Organic Chemistry , 2nd edition, VEB Deutscher Verlag für Grundstoffindindustrie, Leipzig 1985, ISBN 3-342-00280-8 , p. 403.
- ↑ 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. 3-182.
- ^ R. Hegnauer: Chemotaxonomy of Plants , Volume 1: Thallophyten, Bryophyten; Pteridophytes and gymnosperms, Birkhäuser Verlag, Basel 1962, p. 160 ( limited preview in Google book search).
- ↑ Sabine Wallbaum, Thomas Mehler, Jürgen Martens (1994): Decarboxylation of α-Amino Acids containing two and three Stereogenic Centers: A Simple One-Step Procedure to Prepare Two Opticall Active β-Amino Alcohols and a Bicyclic Pyrrolidine Derivative . In: Synthetic Communications , 24 (10); Pp. 1381-1387; doi : 10.1080 / 00397919408011741 .
