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1 H NMR studies on intramolecular hydrogen bonding in perchlorates of N ‐(pyridyl)amides of 6‐methylpicolinic acid N ‐oxide
Author(s) -
Brzezinski Bogumil
Publication year - 1979
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270120803
Subject(s) - intramolecular force , hydrogen bond , chemistry , low barrier hydrogen bond , proton nmr , pyridine , proton , dissociation (chemistry) , oxide , stereochemistry , crystallography , medicinal chemistry , molecule , organic chemistry , physics , quantum mechanics
The 1 H NMR spectra of perchlorates of N ‐(pyridyl)amides of 6‐methylpicolinic acid N ‐oxide (PYAP) in CD 3 CN at 100 MHz show two proton signals belonging to two distinct intramolecular hydrogen bonds. The position of these signals is independent of concentration and temperature. That of the proton of the NH ⃛O bond in PYAP is shifted to still lower field than in N ‐(pyridyl)amides of 6‐methylpicolinic acid N ‐oxide (PYA) due to the inductive effect of the pyridine cation and the formation of another intramolecular hydrogen N + H ⃛O bond. The proton of the N + H ⃛O bond interacts strongly with its environment and is highly sensitive to traces of water. Presumably, water leads to dissociation of the intramolecular bond.