Effet de groupe partant dans l'hydrolyse d'orthoesters cycliques: changement de conformère réactif dans l'hydrolyse des diéthoxy-2,2 tétrahydropyrannes
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 [Formula: see text] is characteristic of a phenolate leaving group, i.e. of the rate-determining cleavage of the endocyclic C—O bond in the systems here studied; these results clearly indicate a change in the nature of the reactive conformer in hydrolysis of 2,2-diethoxy tetrahydropyrans.
Keyword(s):
2017 ◽
Vol 38
(10)
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pp. 1138-1142
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Keyword(s):
1974 ◽
Vol 96
(14)
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pp. 4500-4507
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