Epimerization
Under epimerization means the inversion of configuration at an asymmetric carbon atom of a molecule containing two or more asymmetric carbon atoms , wherein the configuration of the other asymmetric carbon atoms is maintained. Epimers are diastereomers that differ in the configuration of only one stereocenter.
Epimerization of D- gluconic acid (left) into the diastereomeric D- mannonic acid (right) under the influence of quinoline. The two epimeric onacids form an equilibrium. D- mannonic acid is partly converted into D- gluconic acid and vice versa.
cis -decalone and trans -decalone are epimers, the latter being more stable. The epimerization takes place in the α-position to the carbonyl group.
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| cis -decalon | trans -decalon |
The epimerization was observed by Emil Fischer in 1890 when D - gluconic acid was heated with quinoline . The D - mannonic acid epimerized at the C2 carbon was obtained as the reaction product .
Individual evidence
- ^ Hans Beyer , Wolfgang Walter : Organic chemistry. S. Hirzel Verlag, Stuttgart, 1984, ISBN 3-7776-0406-2 , p. 401.
- ↑ Michael B. Smith: March's advanced organic chemistry. John Wiley & Sons, 7th edition, 2013, ISBN 978-0-470-46259-1 , p. 667.
- ↑ Emil Fischer: About the optical isomers of grape sugar, gluconic acid and sugar acid . In: Reports of the German Chemical Society . tape 23 , no. 2 , June 1, 1890, p. 2611–2624 , doi : 10.1002 / cber.189002302157 .
Web links
- Entry on epimerization . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.E02166 Version: 2.3.3.