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Characterization of two hydroxytrichloropicolinic acids: application of the one‐bond chlorine‐isotope effect in 13 C NMR
Author(s) -
Irvine Nicholas M.,
Cooper David H.,
Thornburgh Scott
Publication year - 2008
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2196
Subject(s) - chemistry , tautomer , chlorine , carboxylic acid , proton nmr , carbon 13 nmr , chlorine atom , organic chemistry , medicinal chemistry , kinetic isotope effect , computational chemistry , deuterium , physics , quantum mechanics
The structures of 4‐hydroxy‐3,5,6‐trichloropyridine‐2‐carboxylic acid (1a) and 6‐hydroxy‐3,4,5‐trichloro‐2‐carboxylic acid (1b) were verified by the NMR analysis of their corresponding methylated and decarboxylated derivatives 2,3,5‐trichloro‐4‐methoxypyridine (5) and 3,4,5‐trichloro‐2‐methoxypyridine (8), respectively. The 6‐hydroxy isomer (1a) was found to be in equilibrium with its pyridinone tautomer as evidenced by the formation of significant amounts of 3,4,5‐trichloro‐1‐methyl‐6‐oxo‐1,6‐dihydropyridine‐2‐carboxylic acid methyl ester (6b) on exhaustive methylation. The one‐bond chlorine‐isotope effect was used and shown to be an effective tool for the identification of chlorinated carbons in 13 C NMR spectra providing an additional tool for solving structural problems in chlorinated compounds. Copyright © 2008 John Wiley & Sons, Ltd.