Carboxylic acids contain the carboxyl functional group, -COOH, which consists of a carbonyl group attached to a hydroxyl group.

Aldehydes and ketones serve as solvents, starting materials, and reagents in the chemical industry. Examples include formaldehyde used in preserving biological specimens and making bakelite, acetaldehyde in the production of acetic acid and polymers, and benzaldehyde in perfumery and dye ...

Aromatic aldehydes and ketones undergo electrophilic substitution on the aromatic ring, where the carbonyl group acts as a deactivating and meta-directing group.

The Cannizzaro reaction involves self-oxidation and reduction (disproportionation) of aldehydes without an α-hydrogen atom when heated with concentrated alkali. Aldehydes lacking α-hydrogen atoms participate in this reaction.

Cross aldol condensation occurs when two different aldehydes or ketones react. If both have α-hydrogen atoms, it yields a mixture of four products. The aldol reaction of ethanal and propanal illustrates this when carried out in a mixture.

Aldol and ketol products formed in the Aldol reaction readily lose water to form α, β-unsaturated carbonyl compounds, and this reaction is known as Aldol condensation.

The Aldol reaction involves aldehydes and ketones with at least one α-hydrogen reacting in the presence of dilute alkali to form β-hydroxy aldehydes or β-hydroxy ketones. It is catalyzed by dilute alkali.

Aldehydes are easily oxidized to carboxylic acids by various oxidizing agents, including nitric acid, potassium permanganate, Tollens’ reagent, and Fehlings’ reagent. Ketones, on the other hand, undergo carbon-carbon bond cleavage to form a mixture of carboxylic acids under vigorous oxidation ...

Reduction of the carbonyl group to CH₂ occurs with zinc-amalgam and concentrated hydrochloric acid (Clemmensen reduction) or hydrazine followed by heating with sodium or potassium hydroxide in ethylene glycol (Wolff-Kishner reduction).

Aldehydes are reduced to primary alcohols, and ketones to secondary alcohols, using sodium borohydride (NaBH₄), lithium aluminium hydride (LiAlH₄), or catalytic hydrogenation.