H-1-NMR STUDIES ON INTRA-MOLECULAR HYDROGEN-BONDING IN PERCHLORATES OF N-(PYRIDYL)AMIDES OF 6-METHYLPICOLINIC ACID N-OXIDE

The 1H NMR spectra of perchlorates of N‐(pyridyl)amides of 6‐methylpicolinic acid N‐oxide (PYAP) in CD3CN 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 NH ⃛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. Copyright © 1979 Heyden & Son Ltd.