Search:
Computing and Library Services - delivering an inspiring information environment

Intramolecular nucleophilic assistance in the reactions of O,O'-benzylidene catechols

Capon, Brian and Page, Michael I. (1972) Intramolecular nucleophilic assistance in the reactions of O,O'-benzylidene catechols. Journal of the Chemical Society, Perkin Transactions 2 (14). pp. 2057-2062. ISSN 1472-779X

Metadata only available from this repository.

Abstract

3-(2-Hydroxyphenoxy)phthalide is an intermediate in the hydrolysis of OO-(2-carboxybenzylidene) catechol in aqueous buffers of pH 2·9–5. This reaction is general acid catalysed by carboxylic acids and also occurs spontaneously in a reaction which probably involves water as a general acid catalyst. The catalytic constants for the reactions catalysed by acetic and formic acids are similar to those of the analogously catalysed hydrolyses of OO-(4-carboxybenzylidene) catechol, but the catalytic constant for the spontaneous reaction is ca. 30 times greater than that for spontaneous hydrolysis of the latter compound. This is attributed to nucleophilic assistance in reaction of OO-(2-carboxybenzylidene) catechol. In the pH range 2–5, 2,3-OO-(2-carboxybenzylidene)-2,3-dihydroxybenzoic acid is converted into 3-(3-carboxy-2-hydroxyphenoxy)phthalide. The pH-rate profile is bell-shaped but at the maximum the reaction occurs only ca. three times faster than the hydrolysis of 2,3-OO-(4-carboxybenzylidene)-2,3-dihydroxybenzoic acid. The neighbouring carboxylate group of the aldehyde moiety of this acid does not provide appreciable anchimeric assistance in the intramolecularly catalysed opening of the dioxolan ring

Item Type: Article
Subjects: Q Science > Q Science (General)
Q Science > QD Chemistry
Schools: School of Applied Sciences
Related URLs:
Depositing User: Sharon Beastall
Date Deposited: 12 Nov 2009 08:46
Last Modified: 11 Mar 2010 13:56
URI: http://eprints.hud.ac.uk/id/eprint/6195

Item control for Repository Staff only:

View Item

University of Huddersfield, Queensgate, Huddersfield, HD1 3DH Copyright and Disclaimer All rights reserved ©