Effet de groupe partant dans l'hydrolyse d'orthoesters cycliques: changement de conformère réactif dans l'hydrolyse des diéthoxy-2, 2 tétrahydropyrannes

G Lamaty, P Lorente, C Moreau

Index: Lamaty, Gerard; Lorente, Philippe; Moreau, Claude Canadian Journal of Chemistry, 1983 , vol. 61, p. 2651 - 2656

Full Text: HTML

Citation Number: 5

Abstract

The rates of hydrolysis of 6-substituted 2, 2-diethoxy 3, 4-dihydro benzo-1-pyrans (X= MeO, Me, H and Cl) were determined at two temperatures in water/dioxane 2: 1 by volume. The observed change of sign of the Hammett ρ constants is characteristic of a phenolate leaving group, ie of the rate-determining cleavage of the endocyclic CO bond in the systems here studied; these results clearly indicate a change in the nature of the reactive conformer in ...