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Effect of the ortho-nitro group on the 13C NMR chemical shifts of substituted pyridines

✍ Scribed by Danuta Rasala; Ryszard Gawinecki

Publisher
John Wiley and Sons
Year
1993
Tongue
English
Weight
580 KB
Volume
31
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

The ^13^C NMR spectra of 40 vicinally substituted 2‐ and 3‐nitropyridines were recorded. The observed chemical shifts are, in general, non‐additive. These results are discussed in terms of the effects of 2‐, 3‐ and 4‐substitutents on the ring carbons and of the position of the fixed nitro group and the substituent. The chemical shifts of the para carbon, with respect to the substitutent, follow well the dual substituent parameter approach, which shows their electronic origin. However, the substituent chemical shifts of both ipso and ortho positions can be rationalized, in terms of multiple parameter substituent correlation analysis, only on a approximate level.

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