Theoretical studies of proton transfers

Transfer of a proton from one atom to another hasbeen called "the most general and important reactionin chemistry".' This elementary reaction plays a crucialrole 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 protontransfers in solution, it has been difficult to separateintrinsic characteristics from solvent effects. For example, early solution work explained the decreasingacidity of alcohols arising from larger alkyl substituentsby "electron release" which reduces the stability of theanion relative to the neutral species. However, laterdetermination of a reverse order of acidity in the gasphase4 demonstrated that the trend in solution is dominated by solvent effects and that the alkyl groupsstabilize the negative charge of the anionic species viatheir polarizabilities.