Amides

General structure of carboxamides.
R ¹ , R ² and R ³ stand for a hydrogen atom or an organyl radical. The carbamoyl group is marked blue above and the carbamoyl group substituted by the radicals R ² and R ³ below .

Sulfonic acid amides :
R ¹ , R ² and R ³ stand for a hydrogen atom or an organyl radical

As amides very different chemical compounds are referred to. Amides are predominantly classified in the group of covalent organic compounds , but there are also ionic inorganic amides known as metal amides .

From a purely formal point of view, all amides are derived from ammonia in that one or more hydrogen atoms in the ammonia molecule are replaced by other atoms or groups of atoms. Are there

• Covalent amide derivatives (derivatives) of organic carboxylic acids , sulfonic acids or of inorganic oxo acids (e.g. sulfuric acid or phosphoric acid) in their respective molecules formally one or more of the acidic hydroxyl group (s) in the carboxy group or in the inorganic oxo acid an amino group possiblysubstitutedby alkyl radicals has beenreplaced.
• Ionic amides (metal amides ) should be understoodas salts of ammonia (NH ₃ ), which are formed when a proton in the ammonia molecule is replaced by a metal cation. Reactions for the production of such metal amides take place (in the absence of water!) With the evolution of hydrogen when alkali metals are broughtinto contactwith liquid ammonia . This creates alkali metal amides, e.g. B. Sodium amide (NaNH ₂ ). With their help, other metal amides such. B. silver amide .

Covalent amides

Three blue marked amide bonds
(= peptide bonds)
in a tetrapeptide ( Ala - Ser - Gly - Leu )

Covalent amides are found, among other things, as

• Carboxamides as derivatives of carboxylic acids ,
  • Lactams as cyclic carboxamides
  • Imides as secondary carboxamides
• Peptides and proteins are widespread in nature and contain peptide bonds . Peptide bonds are also amide bonds; Peptides and proteins are also carboxamides.
• Polyamides in certain plastics and synthetic fibers,
• Sulfonic acid amides as derivatives of sulfonic acids in some drugs ,
• Phosphoric acid amides (drugs such as cyclophosphamide , ifosfamide ) as derivatives of various phosphoric acids and
• Polyaminoamides , which are used, among other things , as hardener components for epoxy resins .

The imidic acids form a tautomeric structure in which the double bond is not between carbon and oxygen but between carbon and nitrogen and at the same time a hydroxyl group is present .

Web links

Commons : Amide  - collection of images, videos and audio files

Individual evidence

1. ↑ Entry on amides . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.A00266 Version: 2.3.3.
2. ^ MD Lechner, K. Gehrke, EH Nordmeier: Makromolekulare Chemie. A textbook for chemists, physicists, materials scientists and process engineers. 4th edition, Birkhäuser, Basel / Boston, Mass. / Berlin 2010, ISBN 978-3-7643-8890-4 , pp. 121-125.
3. ↑ Entry on imidic acids. In: Römpp Online . Georg Thieme Verlag, accessed on February 23, 2019.