Hydrochloride

In chemistry, hydrochlorides are salts resulting, or regarded as resulting, from the reaction of hydrochloric acid with an organic base (mostly amines). This is also known as muriate, derived from hydrochloric acid's other name: muriatic acid.

For example, reaction of pyridine (C₅H₅N) with hydrochloric acid (HCl) yields pyridine hydrochloride (C₅H₅N·HCl). Even though this style of formula is often used for denoting the hydrochlorides, the dot incorrectly implies that the two molecules are weakly bonded together; rather, what is present is the salt C₅H₅NH⁺ Cl^- with the correct chemical name pyridinium chloride.

Hydrochloric salts are most often referred to by using the name of the base, then simply tagging on hydrochloride or HCl. For example, while crack cocaine is the freebase of cocaine, the salt form is often referred to as cocaine HCl.

Uses

Converting insoluble amines into hydrochlorides is a common way to make them water- and acid-soluble. This is particularly desirable for substances used in medications. Many pharmaceutical substances are prepared as hydrochlorides so that they may be quickly released in the gastrointestinal tract; the body usually absorbs a hydrochloride within fifteen or thirty minutes. Very often hydrochlorides of amines have longer shelf-lives than their respective free bases.

Examples of hydrochlorides in medical uses are many, ranging from over-the-counter sinus relief to antidepressants.

See also

• Free base (chemistry)
• Quaternary ammonium cation