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Solvent Dependence of Inductivity in the Solvolyses of Substituted Norbornyl p-Toluenesulfonates. Norbornanes, Part 14

✍ Scribed by Rolf Bielmann; Marcus Christen; Peter Flury; Cyril A. Grob

Publisher: John Wiley and Sons
Year: 1983
Tongue: German
Weight: 436 KB
Volume: 66
Category: Article
ISSN: 0018-019X
DOI: 10.1002/hlca.19830660727

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✦ Synopsis

Abstract

A comparison of the solvolysis rates of the substituted 2‐exo‐ and 2‐endo ‐norbornyl p‐toluenesulfonates 1, 2, 3 and 4 and the substituted 1‐ and 2‐adamantyl sulfonates 9 and 10, respectively, in 80% ethanol and 97% trifluoroethanol has shown that the sensitivity of rates to the I‐effect of substituents, i.e. the inductivity of these compounds, varies strongly with structure, configuration and solvent. In 97% trifluoro‐ethanol, a solvent of low nucleophilicity and high ionizing power, the inductivities of the 2‐endo‐norbornyl p‐toluenesulfonates 2 and 4 as well as the inductivities of the adamantyl derivatives 9 and 10 were larger than in 80% ethanol. In contrast, the inductivity of the 2‐exo‐norbornyl p‐toluenesulfonates 1 was practically unchanged. It was, therefore, concluded that the transition states for the former compounds are not, or only weakly, bridged, whereas the transition states for the 2‐exo‐norbornyl p‐tolu‐enesulfonates 1 involve graded bridging by C (6). These results confirm that, due to differential bridging strain, 2‐norbornyl cations are anisotropic to polar effects.

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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 solvolysis rate constants __k__ for the 6‐__endo__‐substituted 2‐__exo__‐norbornyl toluenesulfonates **7** have been determined. Values of log__k__ correlate well with the respective inductive constants of the substitutents except when the latter are nucleophilic and therefore lead