Walden inversion

Walden inversion

Walden inversion is the inversion of a chiral center in a molecule in a chemical reaction. Since a molecule can form two enantiomers around a chiral center, the Walden inversion converts the configuration of the molecule from one enantiomeric form to the other. For example, in a SN2 reaction, Walden inversion occurs at a tetrahedral carbon atom. It can be visualized by imagining an umbrella turned inside-out in a gale.

It was first observed by chemist Paul Walden in 1896. He was able to convert one enantiomer of a chemical compound into the other enantiomer and back again in a so-called Walden cycle which went like this: (+) chlorosuccinic acid (1 in "scheme 1") was converted to (+) malic acid 2 by action of silver oxide in water with retention of configuration, in the next step the hydroxyl group was replaced by chlorine to the other isomer of chlorosuccinic acid 3 by reaction with phosphorus pentachloride, a second reaction with silver oxide yielded (-) malic acid 4 and finally a second reaction with PCl returned the cycle to its starting point. [cite journal
title = Ueber die gegenseitige Umwandlung optischer Antipoden
author = P. Walden
journal = Berichte der deutschen chemischen Gesellschaft
volume = 29
issue = 1
pages = 133–138
year = 1896
url =
doi = 10.1002/cber.18960290127


In this reaction the silver oxide in the first step acts as a hydroxide donor and silver does not play an actual role. The intermediates are the carboxyl dianion A which gives an intramolecular nucleophilic substitution to a four-membered β-lactone ring B. The other carboxyl group is also reactive but in silico data show that the transition state for the formation of the three-membered α-lactam is very high. A hydroxyl ion ring-opens the lactam back to the alcohol C and the net effect of two counts of inversion is retention of configuration. ["The Walden cycle revisited: a computational study of competitive ring closure to α- and β-lactones" J. Grant Buchanan, Richard A. Diggle, Giuseppe D. Ruggiero and Ian H. Williams Chemical Communications, 2006, 1106 - 1108 [http://dx.doi.org/10.1039/b517461a Abstract] .]

See also

* Another demonstration of the Walden cycle in the Brook rearrangement.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • walden inversion — ˈwȯldən noun Usage: usually capitalized W Etymology: after Paul Walden died 1957 Latvian organic chemist : an inversion of configuration of one optically active compound into another that may or may not lead to a change in the direction of… …   Useful english dictionary

  • inversion — /in verr zheuhn, sheuhn/, n. 1. an act or instance of inverting. 2. the state of being inverted. 3. anything that is inverted. 4. Rhet. reversal of the usual or natural order of words; anastrophe. 5. Gram. any change from a basic word order or… …   Universalium

  • Walden, Paul — ▪ Latvian chemist born July 14 [July 26, New Style], 1863, Cēsis, Latvia, Russian Empire died Jan. 24, 1957, Gammertingen, W.Ger.       chemist who discovered the Walden inversion, a reversal of stereochemical configuration that occurs in many… …   Universalium

  • inversion — [ ɛ̃vɛrsjɔ̃ ] n. f. • 1529; lat. inversio, de invertere « retourner » I ♦ A ♦ Sens spéciaux 1 ♦ Déplacement (d un mot ou d un groupe de mots) par rapport à l ordre normal ou habituel de la construction. Inversion du sujet dans l interrogation (ex …   Encyclopédie Universelle

  • Inversion de Walden — ● Inversion de Walden substitution de l un des radicaux liés à un carbone asymétrique, qui conduit à un nouveau dérivé ayant la configuration stérique inverse de celle du produit de départ …   Encyclopédie Universelle

  • Inversión de Walden — Montaje, usando modelos de bolas y palos de los tres pasos en una reacción SN2. El nucleófilo está en verde, el grupo saliente en rojo, y los tres sustituyentes adicionales en anaranjado …   Wikipedia Español

  • Inversion de Walden — L inversion de Walden est une inversion de configuration d un centre chiral au cours d une substitution nucléophile bimoléculaire (SN2). Elle porte le nom du chimiste allemand Paul Walden qui l a découverte en 1896 en travaillant sur les… …   Wikipédia en Français

  • Walden — Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. Walden peut faire référence à : Patronyme Walden Bello (1945 ), un écrivain engagé philippin. Paul Walden (1863–1957) est un chimiste allemand (voir… …   Wikipédia en Français

  • Inversion — Diese Seite wird derzeit im Sinne der Richtlinien für Begriffsklärungen auf der Diskussionsseite des Wikiprojektes Begriffsklärungen diskutiert. Hilf mit, die Mängel zu beseitigen, und beteilige dich an der Diskussion! Hinweise zur Überarbeitung …   Deutsch Wikipedia

  • Inversion — Invertierung; Umkehrung; Reversion; Umdrehung * * * In|ver|si|on 〈[ vɛr ] f. 20〉 1. 〈allg.〉 Umkehrung 2. 〈Gramm.〉 Umkehrung der normalen Wortfolge, z. B. grün ist die Heide 3. 〈Mus.〉 Umkehrung, Gegenbewegung einer Tonfolge 4. 〈Med.〉 Umstülpung… …   Universal-Lexikon

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”