Influence of a side-chain on deuterium isotope effects in 13C NMR spectra of some benzene derivatives

P. Novak, D. Vikić-Topić, Z. Meić, E. Gacs-Baitz

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Deuterium-induced isotope effects on 13C chemical shifts were measured in a series of benzene derivatives, viz. toluene, benzoic acid and benzophenone. The effects over two, three and four bonds reflect a dependence on the transmission pathway and the nature of the side-chain. Steric and inductive influences of side-chain lone pair electrons located at the β-position to the phenyl ring account for a lower magnitude and negative sign of some effects in the deuteriated phenyl ring. In monodeuteriated benzophenones isotope effects are transmitted to the second phenyl ring, e.g. in p-deuteriobenzophenone over up to nine bonds. Although the carbonyl group allows only a minor conjugation between the phenyl rings, the extent, the magnitude and the sign of isotope effects resemble those in fully conjugated molecules, indicating a similar transmission mechanism. In polydeuteriated isotopomers, the additivity of isotope effects holds for the majority of carbon atoms. However, in few cases significant deviations exist owing to perturbations in hydrogen-bond dynamics and redistribution of rotamer populations caused by deuteriation. For monodeuteriated isotopomers, a number of 13C-2H coupling constants through one and three bonds are also reported.

Original languageEnglish
Pages (from-to)610-615
Number of pages6
JournalMagnetic Resonance in Chemistry
Volume34
Issue number8
DOIs
Publication statusPublished - Aug 1 1996

Keywords

  • Benzoic acid
  • Benzophenone
  • C NMR
  • Deuterium isotope effects
  • Toluene

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)

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