ABSTRACT
The proton transfer reaction simply enables charge to be dispersed from highly unstable cationic or anionic intermediates thus providing mechanistic routes of lower energy. Organic synthesis and enzymic catalysis are exceptionally important fields which rely on proton transfer as a means of enabling reactions. Proton transfer between electronegative base pairs in hydroxylic solvents occurs by relay through one or more intermediate solvent molecules; the reactions are usually fast and limited by diffusion. The process often exhibits an Eigen-type Bronsted correlation and the number of intervening solvent molecules can be determined by proton inventory studies of the number of protons “in-flight”. Proton transfer concerted with addition at the carbonyl group as well as concerted push-pull mechanisms have been discovered in a number of cases. Catalysis by hydrogen-bonding can be considered in connection with the transition from a stepwise pre-association mechanism to a fully concerted process.
