Sometimes however, the stereochemical course is complicated by intimate ion pairs, whereby the leaving anion remains close to the carbocation, effectively shielding it from an attack by the nucleophile.
Particularly fast reactions can occur by neighbour group participation, with nonclassical ions as intermediates or transition states.
Related terms are alcoholysis (alcohols) and specifically methanolysis (methanol), acetolysis, ammonolysis (ammonia), and aminolysis (alkyl amines).
For example, aqueous solutions of aluminium chloride are acidic due to the aqua-aluminium complex losing protons to water molecules, giving hydronium ions which lowers the pH.
For this reason, ammonolysis may be considered as a special case of solvolysis, as the ammonia is itself dissolved in a solvent.