Ionic Strength Dependence of Protonation Constants of N-Alkyl Substituted Open Chain Diamines in NaClaq

The protonation of nine N -alkyl substitited diamines was studied in NaCl aq in the ionic strength range 0.1 < I /mol·L -1 < 5, at t = 25 °C. The dependence on ionic strength of protonation constants was taken into account by using two different models, namely a Debye−Hückel type equation and a simplified version of Pitzer equations. The dependence on N -alkyl substitution of both protonation constants and their parameters for the medium effects is discussed, and empirical relationships are reported.