Autoprotolysis

{{short description|Transfer of a proton between identical molecules}}

In chemistry, autoprotolysis is a molecular autoionization, a chemical reaction in which a proton is transferred between two identical molecules, one of which acts as a Brønsted acid, releasing a proton that is accepted by the other molecule, which acts as a Brønsted base.{{GoldBookRef|title=autoprotolysis|file=A00531}} Any chemical that contains both acidic hydrogen and lone pairs of electrons to accept {{chem2|H+}} can undergo autoprotolysis.

For example, water undergoes autoprotolysis in the self-ionization of water reaction.

:{{chem2 | 2 H2O <-> OH- + H3O+ }}

For example, ammonia in its purest form may undergo autoprotolysis:

:{{chem2 | 2 NH3 <-> NH2- + NH4+ }}

Another example is acetic acid:

:{{chem2 | 2 CH3COOH <-> CH3COO- + CH3COOH2+ }}