Transfer of a proton from one atom to another has
been called "the most general and important reaction
in chemistry".' This elementary reaction plays a crucial
role in a myriad of processes including acid-base neutralization, electrophilic addition, and a score of enzymatic reactions.* Since most of the vast literature that has accumulated over the concerns proton
transfers in solution, it has been difficult to separate
intrinsic characteristics from solvent effects. For example, early solution work explained the decreasing
acidity of alcohols arising from larger alkyl substituents
by "electron release" which reduces the stability of the
anion relative to the neutral species. However, later
determination of a reverse order of acidity in the gas
phase4 demonstrated that the trend in solution is dominated by solvent effects and that the alkyl groups
stabilize the negative charge of the anionic species via
their polarizabilities.