In chemistry, hydrochlorides are salts resulting, or regarded as resulting, from the reaction of hydrochloric acid with an organic base (mostly amines). An archaic alternative name for "hydrochloride" is muriate, derived from hydrochloric acid's ancient 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.
Converting insoluble amines into hydrochlorides is a common way to make them water-soluble. This is particularly desirable for substances used in medications. The European Pharmacopoeia lists more than 200 hydrochlorides as active ingredients in drugs. Compared to free bases such hydrochlorides 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.
See also 
- P. Heinrich Stahl (Editor), Camille G. Wermuth (Editor): Pharmaceutical Salts: Properties, Selection, and Use, 2. Ed., Wiley, 2011, ISBN 978-3-90639-051-2.
- European Pharmacopoeia 7th Edition 2011, EDQM.