Carboxylic acids undergo decarboxylation, losing carbon dioxide, when heated with sodalime (NaOH and CaO). Kolbe electrolysis involves the decarboxylation of alkali metal salts of carboxylic acids during electrolysis, resulting in hydrocarbons with twice the carbon atoms in the alkyl group.

Carboxylic acids can be reduced to primary alcohols using lithium aluminium hydride or diborane. Diborane is preferable as it avoids reduction of other functional groups.

Direct attachment of groups like phenyl or vinyl increases the acidity of carboxylic acids, contrary to the expected decrease due to resonance effects. This is attributed to the greater electronegativity of the sp² hybridized carbon to which the carboxyl carbon ...

Electron-withdrawing groups enhance carboxylic acid acidity, stabilizing the conjugate base, while electron-donating groups decrease acidity. The increasing acidity order of substituents is Ph < I < Br < Cl < F < CN < NO₂ < CF₃.

Substituents affect carboxylic acid acidity by influencing the stability of the conjugate base. Electron-withdrawing groups increase acidity by stabilizing the conjugate base through inductive and/or resonance effects, while electron-donating groups decrease acidity by destabilizing the conjugate base.