Mutarotation of D(+)-glucose. III. Evidence for cooperative and competitive nucleophilic catalysis by molybdenum(VI) and tungsten(VI) anions
- 1 January 1984
- journal article
- research article
- Published by CSIRO Publishing in Australian Journal of Chemistry
- Vol. 37 (7) , 1411-1426
- https://doi.org/10.1071/ch9841411
Abstract
The rate of mutarotation of α-D(+)-glucose is subject to general base catalysis by a variety of oxo anions. The relative magnitudes of the second-order rate constants are B4O72->W7O246->Mo7O246- > HCO3->WO42->MoO42- Catalysis by W7O246- and Mo7O246- is competitive but that by WO42- and MoO42- is cooperative. A mechanism for catalysis by the polymeric anions is proposed which involves ion-pair formation between the anion and the conjugate acid of glucose. Specifically oriented aquation sheaths about the charged ions cause them to act as enhanced nucleophiles in the rate-determining step to form the aldehyde intermediate. Activation parameters support this model.Keywords
This publication has 2 references indexed in Scilit:
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- The Determination of Enzyme Dissociation ConstantsJournal of the American Chemical Society, 1934