Converting amines into their hydrochlorides is a common way to improve their water solubility, which can be desirable for substances used in medications.
[1] The European Pharmacopoeia lists more than 200 hydrochlorides as active ingredients in medications.
[2] These hydrochlorides, compared to free bases, may more readily dissolve in the gastrointestinal tract and be absorbed into the bloodstream more quickly.
Additionally, many hydrochlorides of amines have a longer shelf-life than their respective free bases.
Amine hydrochlorides represent latent forms of a more reactive free base.