Thermodynamics of the dissociation of aminomethanesulfonic acid and its N-substituted derivatives in aqueous solutions at 293–313 K

Abstract

ΔG, ΔH, and ΔS of the second dissociation step of aminomethanesulfonic acid and its N-methyl, N-hydroxyethyl, N-(tert-butyl), N-benzyl derivatives in aqueous solutions (at the isoelectric point where the ionic strength is 4.75 × 10^–4 М) are determined on basis of pH measurements at 293–313 K. It is found that an increase of the electron-acceptor properties of the substituents at nitrogen atom reduces the effect temperature has on the thermodynamic functions of dissociation. Enthalpy–enthropy compensation at an isothermodynamic temperature of 303 K is recorded.