Thermodynamics of protonation of alkanolamines in aqueous solutions

The equilibrium constants, pKa, for protonation of monoethanolamine (MEA), N-methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propnol (AMP), 2(2-aminoethyl)etanol)amine (AEEA) and piperazine (Pz) have been measured by potentiometric titration at temperatures from 298.15 to 363.15 K. Enthalpies of protonation, ∆Hp, for these amines were measured at 298.15 K in a reaction calorimeter. The pKa results are used for the calculation of other important thermodynamic parameters (∆H, ∆S, ∆CP).