The proton magnetic resonance spectra of pyridine 1-oxides and their conjugate acids
The p.m.r. spectra of eleven pyridine 1-oxides have been measured in carbon tetrachloride, deuterium oxide, and 18N-deuteriosulphuric acid solution (corresponding to the neutral, hydrogen-bonded, and O-protonated species). The average downfield shifts for the α, β-, and γ-proton lines have been calculated and the results are discussed. Electron distributions and coupling constants are compared with those of the corresponding pyridines and pyridinium salts.