Determination of relative gas-phase basicities by the proton-transfer equilibrium technique and the kinetic method in...

It is shown for the first time that a quadrupole ion-trap mass spectrometer permits determination of gas-phase basicities. Two methods for measuring relative values of these molecular parameters are demonstrated, the proton-transfer equilibrium technique and the kinetic method. The proton-transfer equilibrium technique is the more accurate and precise, and is useful for a wider range of relative basicities. The kinetic method proves more valuable for determining basicities of solids, owing to their low volatilities. For example, the basicity of l-adamantanamine has been measured for the first time and found to be 903.9 +/- 0.8 kJ/mole. Basicity values found for substituted pyridines agreed with the literature values to within 1 kJ/mole.