Deprotonation is the removal of a proton from an atom, ion or molecule. Protonation is the addition of a proton (H+) to an atom, ion or molecule. Protonation and deprotonation are important parts of any chemical reaction.
Example of Protonation
An example of protonation is the reaction between hydrochloric acid (HCl) and water (H2O) to form hydronium ion (H3O+) and chloride ion (Cl-):
HCl + H2O → H3O+ + Cl-
In this reaction, HCl donates a proton (H+) to a water molecule, resulting in the formation of the hydronium ion (H3O+). The chloride ion (Cl-) is formed when the HCl molecule loses a proton. The net effect of this reaction is the transfer of a proton from HCl to water, which results in the formation of an acidic solution due to the presence of hydronium ions.
Example of deprotonation
An example of deprotonation is the reaction between acetic acid (CH3COOH) and water (H2O) to form hydronium ion (H3O+) and acetate ion (CH3COO-):
CH3COOH + H2O ⇌ H3O+ + CH3COO-
In this reaction, the protonated form of acetic acid (CH3COOH) donates a proton (H+) to a water molecule, resulting in the formation of the hydronium ion (H3O+). The acetate ion (CH3COO-) is formed when the acetic acid molecule loses a proton. The net effect of this reaction is the transfer of a proton from acetic acid to water, which results in the formation of an acidic solution due to the presence of hydronium ions. However, the reaction is reversible and the acetate ion can also accept a proton from water to reform acetic acid. This process is known as reverse protonation or deprotonation.