## Abstract A study has been made of the ^13^C chemical shifts of a number of acyclic alkanes, alkenes, nitriles and ketones which contain quaternary carbon atoms. Similar data have also been obtained for the series of compounds involved in the synthesis of triisopropylacetic acid. Substituent effe
13C NMR of organosulfur compounds the 13C chemical shifts of monocyclic γ- and δ-sultones
✍ Scribed by Michael B. Smith; Joseph Wolinsky
- Publisher
- John Wiley and Sons
- Year
- 1982
- Tongue
- English
- Weight
- 477 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
The ^13^C NMR spectra of several monocyclic γ‐sultones(1,2‐oxathiolane 2,2‐dioxides) and δ‐sultones(1,2‐oxathiane 2,2‐dioxides) have been determined and are presented herein. The chemical shifts of the ring carbons of these compounds are compared in terms of conformational, electronic and anisotropic differences. Electric field effects may be responsible for the chemical shifts of the C‐α carbon, but do not appear to be important for C‐α. Anisotropic deshielding also appears to be important for the chemical shifts of C‐α, but the effects on C‐α appear to be small. Dipole changes at C‐α and C‐α, induced by back donation of electron density from the ring oxygen to sulfur, may explain the chemical shifts at C‐α. Substituent effects are readily explained in terms of well‐known effects. In general, the carbons closest to the sulfonate group are found to be the most affected, and the carbons of the δ‐sultones proximate to the sulfonate group are found to be more deshielded than those of the γ‐sultones.
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Before and after cis-trans isomerization, the observed 13 C-NMR chemical shifts of poly(phenylacetylene) (PPA) in the solid state were investigated on the basis of 13 C-NMR chemical shift calculations within AM1 for the cis-transoidal and deflected trans-transoidal forms. Two 13 C-resonance peaks in
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