The dissociation constants of the methylammonium ions and the basic strengths of the methylamines in water

The dissociation constants of the three substituted methylam monium ions have been determined in water at 10° intervals from 0 to 50° C. From these results values have been derived and tabulated for the free energies of dissociation, heats of dissociation, entropies of dissociation and the heat capacity changes for these ions, as well as the corresponding quantities for the ionization of the amines. The heat capacity changes are discussed and it is shown that they can not be interpreted by simple electrostatic theory . It is shown that the anomalous order of the basic strengths of the amines probably disappears at low temperatures.