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Dependence of 13C NMR methoxy substituent chemical shift values on π-bond orders of fused aromatic compounds

✍ Scribed by Pedro Joseph-Nathan; Cirilo García-Martínez; Martha S. Morales-Ríos

Publisher
John Wiley and Sons
Year
1990
Tongue
English
Weight
314 KB
Volume
28
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

The substituent chemical shift values induced by the methoxy group at the two ortho positions of aromatic compounds which include naphthalenes, quinolines, indoles, coumarins, flavones and benzofurans were linearly correlated with π‐bond orders, affording the equation Δδ~ortho~(^13^C) = ‐98.68__P__~π~ + 50.38 (correlation coefficient = 0.929; root mean square error = 1.95 ppm) when 40 pairs of values are considered. Elimination of six points corresponding to ring‐junction quaternary carbons improves the correlation coefficient to 0.961 (root mean square error = 1.4 ppm) for the equation Δδ~ortho~(^13^C) = ‐126.85__P__~π~ + 69.66.

📜 SIMILAR VOLUMES

Dependence of one-bond deuterium isotope
Dependence of one-bond deuterium isotope shifts in 13C NMR on CH bond lengths for substituted and unsubstituted aromatic compounds
✍ Yasuki Nakashima; Takashi Teranishi; Toshiya Suzuki; Tyo Sone; Kensuke Takahashi 📂 Article 📅 1994 🏛 John Wiley and Sons 🌐 English ⚖ 319 KB

## Abstract One‐bond deuterium‐induced isotope shifts of ^13^C NMR (^1^Δ) for 106 sp^2^‐hybridized carbons are discussed in terms of CH bond lengths. ^1^Δ correlates linearly with the related CH bond length calculated by the MNDO MO method by the equation ^1^Δ(ppb)=8350 __r__~CH~ (Å) – 8824.