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Published February 1979 | public
Journal Article

Nitrogen-15 Nuclear Magnetic Resonance Spectroscopy. Pyridine N-Oxides and Quinoline N-Oxides

Abstract

The noise-decoupled nitrogen-15 NMR spectra of ten pyridine N-oxides and two quinoline N-oxides have been obtained at the natural-abundance level by high-resolution NMR spectroscopy. Substituents at the 4-ring position of pyridine N-oxide, capable of resonance interaction with the N-O moiety, give fairly large shifts in the expected directions. Spectra taken in dimethyl sulfoxide solution give 5–20 ppm and 33–55 ppm downfield shifts with respect to the solutions of the same substances in 2,2,2-trifluoroethanol and trifluoroacetic acid. Solvent influences are discussed in terms of hydrogen bonding and protonation of the N-oxide oxygen. Carbon-13 chemical shifts and one-bond carbon-hydrogen coupling constants of some substituted pyridine N-oxides are reported and discussed.

Additional Information

© 1979 Heyden & Son Ltd. Received 13 February 1978; accepted 30 March 1978. Supported by the Public Health Service, Research Grant No. GM-11072 from the Division of General Medical Sciences, and by the National Science Foundation.

Additional details

Created:
August 19, 2023
Modified:
October 25, 2023