ABSTRACT
The nomenclature of Chemical Abstracts is based on the names of heterocycles up to ten-numbered lactam rings. Provided that the parent heterocycle is unsaturated, the name of the saturated lactam must comprise a prefix, e.g., hexahydro, octahydro, or, generally, perhydro. The spatial electron distribution of the amide group is often approximated by discrete values of the partial charges on various atoms. These are obtained by empirical calculations from experimental dipole moments, or by parametrization of charges to fit crystal structures, sublimation energies, spectroscopic or other experimental data, but most often by quantum chemical methods. The lactam can also form molecular complexes with electron donors owing to its acid hydrogens and an electrophilic nature. Self-associations of lactams were studied most often but other complexes with donors much less. Basicity in the lactam series can be quantitatively evaluated by means of the equilibrium constants of any of the mentioned reactions.
