Thermodynamics of protonation of alkanolamines in aqueous solutions

The equilibrium constants, , 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, ΔHp, for these amines were measured at 298.15 K in a reaction calorimeter and compared to those calculated from the experimental values. The effect of the ionic strength of the solution on the equilibrium constants and enthalpy of protonation of MDEA was studied.