Hydroiodide is a collective term for the organochemical class of salts that hydroiodic acid HI forms with basic organic compounds. Hydroiodides are formed, for example, from amines, basic amino acids , amino acid esters and alkaloids . The drug D- glucosamine is available as a hydroiodide.
- R 3 N + HI → R 3 NH + I -
The reaction is analogous to the reaction of ammonia with HI, in which ammonium iodide (NH 4 I) is formed. Like all iodides, hydroiodides contain the iodide anion (I - ) and are therefore salts. Compared to their parent compounds (mostly amines), hydroiodides are usually more water-soluble and can be more easily purified by recrystallization . The hydroiodides of amines are significantly more stable and more resistant to aging - recognizable by their discoloration - than the free basic amines.
In the case of complex molecules with several basic reacting functional groups (see alkaloids , lysine ), in which the protonated group cannot be precisely defined, hydroiodides are often represented graphically as follows:
- R 3 N + HI → R 3 N · HI
The reaction of organic diamines with excess hydroiodic acid produces dihydroiodides , which contain two equivalents of hydroiodic acid (HI) in a salt-like manner.
- Axel Kleemann , Jürgen Engel, Bernd Kutscher and Dietmar Reichert: Pharmaceutical Substances , 4th edition (2000), Thieme-Verlag Stuttgart, ISBN 978-1-58890-031-9 .