Lactam

Lactams (singular: the lactam; Synonym: intramolecular cyclic amide, portmanteau of lactone and amide ) is called molecules in organic chemistry, which contain an amide bond between an amino and a carboxyl group of the same cyclic molecule.

Throughout the nomenclature, the name of lactams Greek letters are preceded by indicating how many carbon atoms in the ring adjacent to the carbonyl carbon are present. You also specify the initial constancy of the carboxyl to the amino group in the corresponding amino carboxylic acid. So, for example, has a δ -lactam four carbon atoms, the carbonyl carbon and the nitrogen, so that a six-membered ring is present; in the Ausgangsaminocarbonsäure the amino group is δ - continuously to the carboxyl group. However, halfway stable are only γ - and δ -lactams. But even they are cleaved by alkalis and acids in the heat in the corresponding amino carboxylic acids. At even greater distance between the amino and carboxy lactams are unstable and split in the presence of a little water in ω -amino acids that easily condense to form macromolecules.

Properties

Lactams with a suitable substitution patterns are subject to the lactam lactim tautomerism. example:

Production

Example of a lactam formation of γ -aminobutyric acid (GABA ) for γ - butyrolactam:

Similar manner, other lactams usually made ​​from ω -amino carboxylic acids by ring closure with elimination of water. From open-chain amides having at least at both ends of the molecule each having a carbon-carbon double bond can also be synthesized by ring -closing metathesis lactams.

ε -caprolactam can be prepared via the acid-catalyzed Beckmann rearrangement of the oxime of cyclohexanone. Over 2 million tonnes of ε -caprolactam are produced.

Use

ε -caprolactam forms chain-like macromolecules that are known as a plastic under the name of nylon and are produced on an industrial scale. Thiolactams can be prepared from lactams by the reaction with Lawesson's reagent or phosphorus pentasulfide.

Examples

  • β -lactam antibiotics
  • Beckmann rearrangement
Proline Greek alphabet Lawesson's reagent Chemiker-Zeitung
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