Determination of p K a values using 15 N and 13 C nuclear magnetic resonance spectroscopy. The case of apramycin

By comparison of p K a values derived from 15 N and 13 C nuclear magnetic resonance (NMR) spectroscopies, the assignment of the 15 N resonances of apramycin is completed. 13 C NMR spectra appear to provide accurate p K a determinations with this aminoglycoside. Hydroxylation adjacent to one of the basic nitrogens of apramycin appears to change the p K a values of all five amines of the molecule.