carbossilico

The term carbossilico refers to the carboxyl functional group in organic chemistry, typically denoted as -COOH. This group consists of a carbonyl group (C=O) adjacent to a hydroxyl group (–OH) attached to the same carbon atom within a larger carbon skeleton. It is the defining feature of carboxylic acids, a broad and important class of compounds.

In terms of structure, the carboxyl group exhibits resonance between two canonical forms, which distributes electron density between the carbonyl oxygen and the hydroxyl oxygen. In its deprotonated form, the carboxylate anion (R–COO−) is stabilized by resonance, contributing to the characteristic acidity of carboxylic acids. This acidity arises from the relatively stable conjugate base formed after deprotonation.

Carboxyl groups are widespread in biology and industry. They appear in amino acids, fatty acids, simple organic acids, and many polymers. They impart polarity to molecules, influence solubility, and enable hydrogen bonding, which affects boiling points and solubility patterns. Carboxylic acids are typically weak acids in water, with pKa values around 4–5 for many small examples; solubility in water decreases as the hydrocarbon portion grows.

Key reactions involve the carboxyl group transforming into derivatives such as esters (via Fischer esterification with alcohols), amides (with amines), or acid chlorides (leading to anhydrides). Reduction can convert carboxyl groups to primary alcohols; decarboxylation can occur under specific conditions, especially for beta-keto acids or with catalytic heating. The carboxyl group also forms salts known as carboxylates with metals or other cations.

In nomenclature, the group is commonly called the carboxyl group; in IUPAC, compounds bearing it are named as carboxylic acids, with the suffix -oic acid.