Spectroscopic studies on olefins—III: NMR of cis- and trans- disubstituted olefins

✍ Scribed by F. H. A. Rummens; J. W. de Haan

• Book ID: 102525276
• Publisher: John Wiley and Sons
• Year: 1970
• Tongue: English
• Weight: 362 KB
• Volume: 2
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270020406

✦ Synopsis

Abstract

The proton NMR spectra of four cis/trans pairs of 1,2‐disubstituted olefins have been analysed. The observed trends of the olefinic, vicinal and allylic proton‐proton coupling constants are discussed in terms of rehybridization at the sp^2^ carbon atoms. It is found that in these substances the trans‐allylic couplings are generally more negative than the cis‐allylic couplings contrary to Barfield's^1^ theoretical prediction but in agreement with some earlier experimental data. Steric hindrance between cisoid substituents is cited as the probable origin of this end related trends.