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Reinterpretation of curved hammett plots in reaction of nucleophiles with aryl benzoates: Change in rate-determining step or mechanism versus ground-state stabilization

Title
Reinterpretation of curved hammett plots in reaction of nucleophiles with aryl benzoates: Change in rate-determining step or mechanism versus ground-state stabilization
Authors
Um I.-H.Han H.-J.Ahn J.-A.Kang S.Buncel E.
Ewha Authors
엄익환
SCOPUS Author ID
엄익환scopusscopus
Issue Date
2002
Journal Title
Journal of Organic Chemistry
ISSN
0022-3263JCR Link
Citation
vol. 67, no. 24, pp. 8475 - 8480
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
A kinetic study is reported for the reaction of the anionic nucleophiles OH-, CN-, and N3- with aryl benzoates containing substituents on the benzoyl as well as the aryloxy moiety, in 80 mol % H2O-20 mol % dimethyl sulfoxide at 25.0 °C. Hammett log k vs σ plots for these systems are consistently nonlinear. However, a possible traditional explanation in terms of a mechanism involving a tetrahedral intermediate with curvature resulting from a change in rate-determining step is considered but rejected. The proposed explanation involves ground-state stabilization through resonance interaction between the benzoyl substituent and the electrophilic carbonyl center in the two-stage mechanism. Accordingly, the data are nicely accommodated on the basis of the Yukawa-Tsuno equation, which gives linear plots for all three nuceophiles. Literature reports of the mechanism of acyl transfer processes are reconsidered in this light.
DOI
10.1021/jo026339g
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자연과학대학 > 화학·나노과학전공 > Journal papers
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