𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Carbon-13 NMR spectra of monosulphones and disulphones: Substitution rules and conformational effects

✍ Scribed by A. H. Fawcett; K. J. Ivin; C. D. Stewart

Publisher
John Wiley and Sons
Year
1978
Tongue
English
Weight
918 KB
Volume
11
Category
Article
ISSN
0749-1581

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

Carbon‐13 NMR spectra have been obtained for 27 aliphatic monosulphones and 13 aliphatic disulphones. Substitution rules have been formulated which allow the prediction of chemical shifts when a CH~2~ group in a hydrocarbon is replaced by an SO~2~ group, or when an H atom in a sulphone is replaced by an alkyl group. Carbon atoms β to a sulphone group show a marked upfield shift effect which is sensitive to the conformation about the CS bond; atoms in the trans position experience an upfield shift (−9.39±1.64 ppm) compared with those in the gauche position. An assignment of the meso (m) and racemic (r) β‐carbon peaks in di‐sec‐butyl sulphone was made by synthesis of the optically active compound. |δ~m~–δL~r~| decreases with increasing temperature for both β–carbon atoms; this effect was interpreted in terms of two available conformers for each of the m and r compounds, those for the m form having the same energy and entropy, and those for the r form having Δ__S__=0.6 J K^−1^ mol^−1^ and Δ__H__=0.8 kJ mol^−1^. Observed chemical shifts for the disulphones were compared with those estimated by the application of the first set of substitution rules.

📜 SIMILAR VOLUMES

Carbon-13 NMR spectra of 3-aryl-2-thioxo
Carbon-13 NMR spectra of 3-aryl-2-thioxo-4-imidazolidinones. Conformational isomerism and substituent effects
✍ Mohammad A. Khadim; Lawrence D. Colebrook 📂 Article 📅 1981 🏛 John Wiley and Sons 🌐 English ⚖ 443 KB

## Abstract A ^13^C NMR study of a series of 3‐aryl‐2‐thioxo‐4‐imidazolidinones, which are capable of existing as enantiomeric or diastereomeric rotational isomers about the aryl CN bond, shows that rates of internal rotation are slow at the probe temperature. The effects of hetero‐ and aryl‐ring

Carbon-13 NMR spectra of some 4- and 5-s
Carbon-13 NMR spectra of some 4- and 5-substituted pyrimidines
✍ Gordon W. H. Cheeseman; Christopher J. Turner; Desmond J. Brown 📂 Article 📅 1979 🏛 John Wiley and Sons 🌐 English ⚖ 299 KB

## Abstract Carbon‐13 NMR chemical shifts and carbon‐proton coupling constants for nine 4‐substituted and six 5‐substituted pyrimidines are reported. The carbon chemical shifts are correlated with π‐electron densities. Carbon‐proton coupling constants fail to correlate with substituent electronegat

Carbon-13 NMR spectra of some 4-substitu
Carbon-13 NMR spectra of some 4-substituted phenacyl chlorides and iodides
✍ Paulo Roberto Olivato; Sandra Alvarez Guerrero; Roberto Rittner 📂 Article 📅 1987 🏛 John Wiley and Sons 🌐 English ⚖ 165 KB

The 13C NMR signals for some 4-substituted phenacyl chlorides and iodides were assigned. The carbonyl carbons exhibit upfield shifts compared with those of the corresponding Csubstituted acetophenones; in the chlorinated derivatives a downfield shift is observed for the cu-methylene carbons, while a