3.3. Piperazine (PZ)
PZ is a secondary diamine so to model its chemistry requires
the inclusion of reactions Eqs. (6)–(8), protonation of the monocarbamate,
dicarbamate formation and dicarbamate protonation
respectively. For other diamines a second protonation of the amine
may be required but in the case of piperazine it can be neglected