Hydroxy group

In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula−OH and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy groups. Both the negatively charged anionHO, called hydroxide, and the neutral radicalHO·, known as the hydroxyl radical, consist of an unbonded hydroxy group.

According to IUPAC definitions, the term hydroxyl refers to the hydroxyl radical (·OH) only, while the functional group −OH is called a hydroxy group.