chlorohydrate

Chlorohydrate, more commonly referred to as hydrochloride or chlorhydrate, is a class of salts formed when a basic compound, typically an amine, reacts with hydrochloric acid. In the resulting salt, the base is protonated to form a positively charged species (BH+) paired with a chloride counterion (Cl−). The general representation is BHCl, though in solid form the salt is more accurately described as [BH]+Cl−. The term chlorohydrate is found in older literature or alternative spellings.

Formation and properties

Chlorohydrates are produced by acid–base neutralization reactions between a base and hydrochloric acid, often followed by purification such as crystallization from water or suitable solvents. They are usually highly soluble in water and form crystalline solids. The exact properties depend on the parent base, but chlorohydrates are generally stable at room temperature and can be hygroscopic.

Uses

Chlorohydrates are widely used in pharmaceuticals to improve solubility, stability, and bioavailability of active compounds. Many drugs are prescribed as hydrochloride salts rather than their free bases. Common examples include morphine hydrochloride, lidocaine hydrochloride, and diphenhydramine hydrochloride. Cocaine hydrochloride is another well-known example, historically used as a local anesthetic and, in different contexts, as a controlled substance.

Safety

Chlorohydrates should be handled with care as they are salts formed from hydrochloric acid. They can be corrosive to skin and eyes and may pose inhalation hazards in powder form. Proper storage and handling per chemical safety guidelines are required.

See also

Hydrochloride; salt; acid–base chemistry.