Use of Substituent Effects on Isotope Effects to Distinguish between Proton and Hydride Transfers. Part II. Mechanism of Decarboxylation of β-Keto Acids in Benzene1- …

CG Swain, RFW Bader, RM Esteve Jr…

Index: Swain,C.G. et al. Journal of the American Chemical Society, 1961 , vol. 83, p. 1951 - 1955

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Citation Number: 49

Abstract

Isotope effects (k~ coo=/k~ coo~) in the decarboxylation of substituted benzoylacetic acids in benzene at 50'are 2.8 for m-nitro, 1.7 for p-chloro, 1.4 for unsubstituted, and 0.85 for p- methyl, although these substituents have a negligible effect on OH frequencies in the ground state. This large variation in isotope effect with substituents is inconsistent with a cyclic hydride transfer mechanism but in accord with a cyclic proton transfer mechanism.