Protonation plays a crucial role in catalysis by altering the electronic structure and reactivity of substrates. In acid catalysis, for example, protonation can activate a substrate by making it more electrophilic, thus facilitating nucleophilic attack. Conversely, in base catalysis, the removal of a proton (deprotonation) can make a substrate more nucleophilic. Protonation can also stabilize reaction intermediates, lowering the activation energy and speeding up the reaction.
