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The role of linear electric field effects in halogen induced 13C chemical shifts in cyclohexanes and methylenecyclohexanes

✍ Scribed by Marianne E. Van Dommelen; Jan W. de Haan; Henk M. Buck

Publisher: John Wiley and Sons
Year: 1980
Tongue: English
Weight: 297 KB
Volume: 13
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1270130611

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✦ Synopsis

Abstract

The ^13^C NMR chemical shifts of methylenecyclohexane at low temperature are compared with those of 4‐chloro‐ and 4‐bromo‐methylenecyclohexane under the same conditions. It is concluded that the halogen induced shift differences at the double bond are to be ascribed largely to linear electric field (LEF) effects. At the same time, doubt is expressed concerning similar explanations for C‐4 in halo‐substituted cyclohexanes. The large influence of using different values of longitudinal bond polarizabilities is demonstrated. Finally, some remarkable long‐range shift effects on double bonds are described for geranyl chloride and geranyl bromide.

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