carbonilo

Carbonilo, or the carbonyl group, refers to a functional group consisting of a carbon atom double-bonded to an oxygen atom (C=O). It is a defining feature of a broad family of organic compounds, including aldehydes, ketones, carboxylic acids and their derivatives such as esters, amides, anhydrides, and acid chlorides. The carbonyl carbon is typically electrophilic, making carbonyl compounds versatile intermediates in organic synthesis.

Structurally, the C=O bond is polar, with oxygen bearing a partial negative charge and the carbon bearing a partial positive charge. The geometry around the carbonyl carbon is usually planar (sp2). Resonance delocalization between the oxygen lone pairs and the carbonyl π system contributes to the bond character and reactivity. The carbonyl group is commonly identified by characteristic infrared absorption around 1700 cm−1, though the exact frequency varies with substituents and ring strain. In 13C NMR spectroscopy, the carbonyl carbon typically resonates downfield, around 180–220 ppm.

Nomenclature centers on the carbonyl as the principal functional group. Aldehydes end with the suffix -al (for example, formaldehyde, CH2O; acetaldehyde, CH3CHO), while ketones end with -one (for example, acetone, (CH3)2CO). Carboxylic acids and their derivatives also feature a carbonyl, with corresponding prefixes or suffixes reflecting the attached groups.

Reactivity is dominated by the electrophilic carbon. Carbonyls undergo nucleophilic addition reactions, giving products such as alcohols (reduction), hydrates, acetals/ketals, and imines. Aldehydes can be oxidized to carboxylic acids; ketones can be reduced to secondary alcohols. Hydration and formation of acetals are common in the presence of alcohols under acid catalysis. The carbonyl group thus plays a central role in both organic synthesis and biochemistry.