Hydrobromides

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Hydrobromide is a collective term for the organochemical class of salts that hydrobromic acid (HBr) forms with basic organic compounds. Often, hydrobromides are salts of primary, secondary or tertiary amines that are formed in a neutralization reaction with hydrobromic acid (HBr):

R 3 N + HBr → R 3 NH + Br -

The reaction proceeds analogously to the reaction of ammonia with HBr, in which ammonium bromide (NH 4 Br) is formed. Like all bromides, hydrobromides contain the bromide anion (Br - ) and are therefore salts. Compared to their parent compounds (mostly amines), hydrobromides are usually more water-soluble and can be more easily purified by recrystallization . The hydrobromides 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, hydrobromides are often represented graphically as follows:

R 3 N + HBr → R 3 N • HBr

The reaction of organic diamines with excess hydrobromic acid produces dihydrobromides which contain two equivalents of hydrobromic acid (HBr) in a salt-like manner.

In addition, hydrobromids are formed from basic amino acids , amino acid esters and alkaloids . A number of drugs (examples: citalopram , dextromethorphan , fenoterol , galantamine , salsolinol ) are commercially available as hydrobromides. [Wick cough syrup ® (D)] and Homatropin [Homatropin POS ® 1% (D)] are further examples. The drugs scopolamine and eletriptan are also used as hydrobromides.

See also

Individual evidence

  1. ^ Axel Kleemann , Jürgen Engel, Bernd Kutscher and Dietmar Reichert: Pharmaceutical Substances , 4th edition (2000), Thieme-Verlag Stuttgart, ISBN 978-1-58890-031-9 .
  2. ↑ European Pharmacopoeia 1997, pp. 1611–1612.
  3. ^ The Merck Index . An Encyclopaedia of Chemicals, Drugs and Biologicals . 14th edition, 2006, p. 602, ISBN 978-0-911910-00-1 .
  4. ^ P. Heinrich Stahl (editor), Camille G. Wermuth (editor): Pharmaceutical Salts: Properties, Selection, and Use , 2nd edition, Wiley, 2011, ISBN 978-3-90639-051-2 .