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Polar Effects in the Solvolysis of 4-Substituted Bicyclo [2.2.2]octyl p-Nitrobenzenesulfonates. Polar effects. VII

✍ Scribed by Cyril A. Grob; Roland Rich

Publisher
John Wiley and Sons
Year
1979
Tongue
German
Weight
415 KB
Volume
62
Category
Article
ISSN
0018-019X

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✦ Synopsis

Hydrolysisofbicyclo[2.2.2]octylp-nitrobenzenesulfonate (14a,X =p-N02C6H4S03), and nineteen 4-R-substituted derivatives 14b-14 t in 70% aqueous dioxane yield the corresponding bicyclo [2.2.2]octanols 14 (X = OH), exclusively. The 7-center fragmentation to 1,4-dimethylidene-cyclohexane (15) is not observed. The logarithms of most of the rate constants, measured in 80% ethanol, correlate well with the corresponding inductive substituent constants a? of R. Hence, in these cases ionization rate is controlled by the inductive effect of R only. Poor correlations result when the substituents are potentially electrofugal groups, such as COO-, CH,OH, CH,NH,, CONH, and H, the deviations from the inductive regression line corresponding to rate enhancements of 1.6 to 8. These exalted substituent effects are tentatively ascribed to extended hyperconjugation involving two a-bonds. This study corroborates previous evidence that the inductive effect alone does not fully account for the polar effect of some substituents in reactions involving carbocations.

📜 SIMILAR VOLUMES

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## Abstract The rate constants for 3‐substituted adamantyl __p__‐toluenesulfonates **3a**‐**3k** in ethanol/water 80:20 correlate well with the respective inductive substituent constants σ. The reaction constant ρ for the toluenesulfonates **3** is 10% larger than for the corresponding bromides **2

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## Abstract The rate constants (log __k__) for the solvolysis of 4^e^‐substituted 2^e^‐ and 2^a^‐adamantyl __p__‐nitrobenzenesulfonates **14** and **15**, respectively, in 80% EtOH correlate linearly with the respective inductive substituent constants σ. Therefore, relative rates are controlled by

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## Abstract The solvolysis rates and products of the 6__endo__‐R‐substituted 2__endo__‐norbornyl toluenesulfonates **6a**–**6i** have been determined. The rates of **6a**–**6g** correlate with the inductive constants σ the 6__endo__‐substituents and are not related to the size of the latter. It is

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## Abstract The second order rate constants (__k__) for quaternization of thirty 4‐substituted quinuclidines (**1**) by methyl iodide in methanol have been measured. The effects of the substituents on rate are relatively small and indicate an early transition state with little charge separation. Th