USE OF GAS-PHASE BASICITIES FOR THE STUDY OF SOLUTION KINETICS - AN UNPRECEDENTED EXTENSION OF BRONSTED CORRELATIONS

Activation free energies for the quaternization of N(sp2 and sp3) n-donor bases (B) with Mel in MeCN at 298 K (reaction i), DELTA-G(Mel)(MeCN), are linearly related to the standard free energy changes for the gas-phase protonation of the same bases (reaction ii), DELTA-G(H+)(g). These LFERs are compared to those relating DELTA-G(H+)(g) and the standard free energy changes [GRAPHICS] for model donor-acceptor reactions in solution. These results shed light on important aspects of the Menshutkin reaction and strongly suggest that, for processes not involving extensive charge dispersal from the solute to the solvent or strongly specific solvent-solute interactions, gas-phase basicities are the choice reference property for Bronsted analyses.