acting as acids. Basic hydroxides, whether solids or in solution, are stored in airtight plastic containers. The hydroxide ion can function as a typical Hydroxide (occasionally hydroxyl ion) is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, ligand, nucleophile, and catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous soluti B(OH)3 + H2O ⇌ B(OH)−4 + H+ A variety of oxyanions of boron are known, which, in the protonated form, contain hydroxide groups. OH− + EtOH ⇌ EtO− + H2O to produce the ethoxide ion. The pKa for self-dissociation of ethanol is about 16, so the alkoxide ion is a strong enough base. The addition of an alcohol to an aldehyde to form a hemiacetal is an example of a reaction that can be catalyzed by the presence of hydroxide. Hydroxide can also act as a Lewis-base catalyst. The hydroxide ion is intermediate in nucleophilicity between the fluoride ion F−, and the amide ion NH−2. Ester hydrolysis under alkaline conditions (also known as base hydrolysis)