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Related to Lactams: lactim



internal cyclic amides of amino carboxylic acids that contain a —CO—NH— group in the ring (I). The tautomeric, enol form of lactam is known as lactim (II):

Lactams are classified as β-, γ-, δ-, ε-, and so forth according to the type of amino carboxylic acids included in their composition, for example, β-propiolactam (III; melting point, 73°-74°C), γ-butyrolactam (IV; melting point, 24.6°C), and ε-caprolactam (V; melting point, 68°-69°C):

Lactams are primarily obtained by the cyclization of amino carboxylic acids or their derivatives [Y—(CH2)nNH2, where Y = COOH, COOR, CONH2, CN], as well as by the cyclization of amides of halogen carboxylic or hydroxycarboxylic acid [X—(CH2)nCONHR, where X = OH or a halogen]. An important method of obtaining lactam is the Beckmann rearrangement of cyclic ketoximes, which is used in the industrial preparation of ε-caprolactam.

Lactams readily undergo alkylation, acylation, and halogena-tion with retention of the ring. The lactam ring, however, is opened at the —CO—NH—bond during hydrolysis, ammonolysis, hydrogenolysis, and polymerization. For example, ε-caprolactam polymerization yields polycaproamide, from which nylon 6 fiber is made. Many lactams are biologically active substances (for example, a molecule of penicillin contains a β-propiolactam residue).

References in periodicals archive ?
This is the first study to demonstrate a suitable enzyme for synthesis of lactams under microbial fermentation conditions for the manufacture of nylon.
The enzyme has a broad substrate spectrum and can turn linear amino acids into their corresponding cyclic lactams when the reaction occurs in Escherichia coli.
The b-lactam antibiotic including penicillins, cephalosporins, cephamycins, monocyclic lactams and other atypical class refers to a large class of antibiotics containing the b-lactam ring structure.
Mitim is private-owned and specializes in the filling of injectable beta lactam products.
Group 2--animals treated with [beta] lactams for mastitis by intramamry application,
The Agrobacterium suppression, obtained with the beta lactams, was definitively verified when regenerated shoots were cultured in MS medium without antibiotics.
1] Today, it is known that the major factor causing [beta]-lactamase production by pathogens is the widespread, injudicious and irrational clinical use of [beta]- lactams.
The steroidal enamine lactam intermediates used as starting materials were prepared as we first described in 1958.
The transaction also cements our leading position in beta lactam production and provides Recipharm not only with additional scale but also opportunities to realise commercial and operational synergies as we combine it with our existing Italian business".
Adds an important technology in the filling of injectable beta lactams with sales to the US and European markets.
Effectiveness of beta lactam antibiotics compared with antibiotics active against atypical pathogens in non-severe community acquired pneumonia: meta-analysis.