Comparison of quantum mechanical and experimental gas-phase basicities of amines and alcohols

A comparison was made between the experimental and B3LYP relative gas-phase basicities and proton affinities of a series of 9 amine, 3 alcohol, and 3 alkanolamine molecules. While agreement is good for most of the species studied, it is poor for the alkanolamines and 1,2-ethanediol. A series of calculations were undertaken at the B3LYP and MP2 levels using various basis sets to see if the uncertainties in the calculations can account for the discrepancies. The results suggest that this is unlikely and that the theoretical values are likely to be reasonably accurate. Calculations are also presented for the dimer formation energies of alkanolamine molecules, diamine molecules, and 1,2-ethanediol. These calculations suggest that all of these species can form proton-bound dimers. The alkanolamines and 1,2-ethanediol also appear to have relatively high formation energies for neutral dimers.