Deprotoneerimise

Deprotoneerimise, in English commonly deprotonation, is the removal of a proton (H+) from a molecule, yielding a conjugate base. It is a central operation in acid–base chemistry and a precursor step in many organic transformations. In Bronsted–Lowry terms, an acid donates a proton and a base accepts it.

The extent of deprotonation in solution is governed by the acid–base equilibrium, often expressed by the pKa of the acidic site and the pH of the medium. A stronger acid (lower pKa) deprotonates more readily. Stabilization of the resulting conjugate base by resonance, electronegativity, or solvation also drives the reaction. The choice of solvent and base strongly influences outcomes, with water, alcohols, and polar aprotic solvents commonly used to tune reactivity.

Typical examples include: deprotonation of carboxylic acids by bases to give carboxylates; deprotonation of alcohols or phenols to form alkoxides or phenoxides; deprotonation of ammonia or amines to form amide or amine anions; deprotonation of terminal alkynes to form acetylide ions; and alpha-deprotonation of carbonyl compounds to form enolates, enabling subsequent alkylation or acylation.

Applications span synthesis and catalysis (for example, enolate chemistry, C–C bond formation, and base-catalyzed transformations), as well as biochemistry, where deprotonation events influence enzyme activity and protein charge states. Reversibility and competition with proton transfer can complicate outcomes, depending on pH, solvent, and base strength. See also pKa, conjugate base, and acid–base equilibria.