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lactam Chem.|ˈlæktæm|
[a. G. lactam (Baeyer & Oekonomides 1882, in Ber. d. Deut. Chem. Ges. XV. 2102), f. lact-on lactone + am-id amide.]
Any of the class of cyclic amides analogous to the lactones, characterized by the group {b1}NH·CO{b1} as part of a ring (lactam ring) and formed by the elimination of a molecule of water from an amino and a carboxyl group of an acid; freq. with prefixed Gr. letter (see lactone 2).
1883Jrnl. Chem. Soc. XLIV. 202 The authors propose the name lactam for bodies formed like acetylisatin, and lactim for those formed like isatin. 1910Encycl. Brit. VI. 59/1 The internal anhydrides of aminocarboxylic acids (lactams, betaines). 1936L. J. Desha Org. Chem. xxvi. 522 Lactam-lactim tautomerism involves the shift of a hydrogen atom from nitrogen to oxygen and vice versa. 1949E. P. Abraham et al. in H. W. Florey et al. Antibiotics II. xv. 669 The four-membered lactam ring which was present in this structure [of penicillin] had not previously been found in natural compounds, and the ease with which it could be broken was responsible for the instability of penicillin under a variety of conditions. 1964Roberts & Caserio Basic Princ. Org. Chem. xx. 712 Formation of α- and β-lactams is expected to generate considerable ring strain, and other more favorable reactions usually intervene. 1966McGraw-Hill Encycl. Sci. & Technol. VII. 377/1 Although γ- and δ-amino acids are nontoxic themselves, the corresponding lactams show pronounced strychnine-type toxicity. |