CoachThe SN1 mechanism (substitution, nucleophilic, unimolecular) has two steps: the slow heterolysis of the C–Y bond, giving a carbocation, then the fast addition of the nucleophile to the carbocation. A reaction that turns a single enantiomer into a mixture of both is a racemisation; a substitution in which the solvent is the nucleophile is a solvolysis.
