Nitrogen-15 Nuclear Magnetic Resonance Spectroscopy. Nitrogen-15 Chemical Shifts Determined from Natural-Abundance Spectra

A number of ^(15)N chemical shifts, determined at the natural-abundance level of the isotope, are reported for some secondary alkylamines, amides, ureas, urethanes, heterocycles, and miscellaneous compounds. Substituent chemical-shift parameters have been derived for secondary-alkylamine ^(15)N chemical shifts. The ^(15)N chemical shifts of secondary alkylamines appear to be potentially useful to determine the number of carbon atoms β to the nitrogen. Effects produced by differences in stereochemistry on the ^(15)N nmr spectra of di-2-butylamine and di-2-hexylamine have been detected. Possible procedures for accounting for changes in diamagnetic shielding between pairs of compounds are discussed