COOHryhmälle

COOHryhmälle is a Finnish term commonly used in chemistry education to refer to the carboxyl functional group, written as -COOH. It is not a distinct chemical species but a label for the reactive moiety found in carboxylic acids and their derivatives.

The carboxyl group consists of a carbonyl carbon double-bonded to oxygen and single-bonded to a hydroxyl group (-COOH). The group is acidic for an organic functional group, able to donate a proton to form the carboxylate anion (-COO−). Substituents and solvent conditions influence its acidity, typically giving pKa values around 4–5 for simple aliphatic acids in water.

Chemical reactions involving the COOH group include esterification with alcohols to give esters, usually under acid catalysis; amidation with amines to form amides; and various decarboxylation processes upon heating or catalysis. Condensation of two carboxyl groups can yield anhydrides under dehydrating conditions. In base, the group can be deprotonated to form salts, such as sodium benzoate.

In biology, carboxyl groups are present in amino acids and fatty acids. At physiological pH, many carboxyl groups exist as carboxylate anions, affecting the molecule’s charge and solubility. The term COOHryhmälle often appears in educational contexts to discuss proton transfer, acidity, and reactivity of the carboxyl group.

See also: Carboxyl group; Carboxylic acid; Esterification; Amide; Carboxylate.