PROTONATION SEQUENCE OF LINEAR ALIPHATIC POLYAMINES BY C-13 NMR-SPECTROSCOPY

The C-13 NMR spectra are reported as a function of pH for 4,7-diazadecane-1,10-diamine, 4,8-diazaundecane-1,11-diamine and 3,6,9-triazaundecane-1,11-diamine. The previously reported amine shift parameters pi and pi(+) are used to determine the protonation sites in the partially protonated intermediate forms of these and a further five polyamines whose C-13-pH profiles have been published. The use of this simple method for determining protonation sequences is examined critically.