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Increments for calculation of the 13C NMR shifts of acetylated polyphenols considering steric interactions

✍ Scribed by S. Wegner-Hambloch; K.-W. Glombitza

Publisher: John Wiley and Sons
Year: 1985
Tongue: English
Weight: 247 KB
Volume: 23
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1260230515

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✦ Synopsis

Considerable deviations in the values obtained are an inherent deficiency in the calculation of 13C NMR chemical shifts of the polyphenolic phlorotannins from brown algae when using increments for mouosubstituted aromatic substances. In order to account for steric interactions within this class of compounds, special increments have been developed by the use of multiple hear regression with dummy variables. With these C NMR chemical shift increments, the occurrence of known and of hitherto unknown substitution patterns can be predicted. l 3

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13C NMR of substituted aryl carbenium ions: Continuous dependence of the ipso substituent shifts upon the carbenium character. Use of proportionality relationships for the evaluation of substituent–substituent interactions

✍ François Membrey; Bernard Ancian; Jean-Pierre Doucet 📂 Article 📅 1978 🏛 John Wiley and Sons 🌐 English ⚖ 366 KB

## Abstract ^13^C substituent shifts in __para__‐substituted phenyl and 2‐phenylethenyl carbenium ions have been studied within the general model of __para__‐disubstituted benzenes XC~6~H~4~Y. Large variations are observed for the __ipso__ shifts induced by the Y substituents (Y = NO~2~. … OCH~3~