hýdroxýl

Hydroxyl refers to a functional group in chemistry composed of one oxygen atom and one hydrogen atom, with the chemical formula −OH. It is a polar group and is often found in organic compounds, where it is responsible for many characteristic properties. The hydroxyl group is the defining feature of alcohols, where it is attached to a saturated carbon atom. For example, ethanol, a common alcohol, has the chemical formula CH3CH2OH.

When a hydroxyl group is bonded to an oxygen atom, it forms a hydroperoxide group (−OOH). In the context of acids, the term "hydroxide" is often used to refer to the anion OH−. This anion is a strong base and is found in many ionic compounds, such as sodium hydroxide (NaOH). The hydroxyl group's ability to form hydrogen bonds significantly influences the physical properties of compounds containing it, such as increasing boiling points and solubility in water. It plays a crucial role in many chemical reactions, including oxidation and reduction processes, and is a fundamental building block in many biological molecules.