This MedLibrary.org supplementary page on Lobry-de Bruyn-van Ekenstein transformation is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
The Lobry-de Bruyn-van Ekenstein transformation also known as the Lobry-de Bruyn-van-Alberda-van-Ekenstein transformation is a base catalyzed Aldose-Ketose-Isomerization in carbohydrate chemistry 1 . A typical rearrangement reaction is that between glyceraldehyde and dihydroxyacetone in a chemical equilibrium.
The reaction is relevant for the industrial production of certain ketoses and was discovered in 1885 by Cornelis Adriaan Lobry van Troostenburg de Bruyn and Willem Alberda van Ekenstein.
Reaction mechanism
The following scheme describes the reaction mechanism where R is any organic residue.
The position of the equilibrium or the reactant to product ratio depends on concentration, solvent,pH value and temperature. At equilibrium the aldose and ketose form a mixture which in the case of the glyceraldehyde and dihydroxyacetone is also called glycerose.
Stereochemistry
The carbon atom at which the initial deprotonation takes place is a stereocenter and based on the equilibrium all reaction steps constitute a epimerization. For example, D-Glucose (an Aldose) rearranges to D-Fructose the ketose. The stereochemical configuration is lost in this reaction in the enol form. In the equilibrium the enol can be protonated from two faces resulting in the backformation of glucose and the formation of D-mannose. The final product is a mix of D-glucose, D-fructose and D-mannose.
References
- ^ ANGYAL, S.J.: The Lobry de Bruyn–Alberda van Ekenstein transformation and related reactions, in: Glycoscience: epimerisation, isomerisation and rearrangement reactions of carbohydrates, Vol. 215, (Ed.: STÜTZ, A.E.), Springer-Verlag, Berlin, 2001, 1–14
Wikipedia content modification information:
- This page was last modified on 18 August 2008, at 09:26.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Lobry-de Bruyn-van Ekenstein transformation".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.