Hüdroksüülrühmals

Hydroxyl groups are a functional group in organic chemistry consisting of an oxygen atom covalently bonded to a hydrogen atom. This combination, represented by -OH, is highly significant due to its impact on the properties of molecules. The presence of a hydroxyl group makes a molecule polar. This polarity arises from the electronegativity difference between oxygen and hydrogen, leading to a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atom. This polarity allows hydroxyl-containing compounds to form hydrogen bonds with water molecules, which is why many such compounds are soluble in water.

Hydroxyl groups are characteristic of alcohols, where they are attached to a saturated carbon atom. They are also found in phenols, where the hydroxyl group is attached to an aromatic ring. In carboxylic acids, the hydroxyl group is part of the carboxyl functional group (-COOH). The reactivity of the hydroxyl group is varied; it can undergo oxidation, substitution reactions, and esterification, among others. The position and number of hydroxyl groups on a molecule can greatly influence its physical and chemical properties, including its boiling point, acidity, and reactivity. This functional group plays a crucial role in many biological molecules, such as carbohydrates and amino acids.