Solvent effect on the protonation of some alkylamines

Abstract

Thermodynamic data were obtained at 25 °C for the solution and protonation of six bases B: ammonia, three methylamines, and monoethyl and n-propylamines in dimethylsulfoxide (Me2SO) and propylene carbonate (PC). Vapour pressure, potentiometric, and calorimetric determinations were carried out. The solvent effect on the basicity order and protonation of the amines is analysed by using gas phase data and comparing the solution thermodynamics of gaseous B and BH+. The heat of solution of B in both solvents is close to its heat of condensation. The solution data for BH+ are discussed in terms of two recent hydration data interpretations.