Dielectric Relaxation of 2‐Pyrrolidinone and Some N‐Substituted, Related Compounds in the Liquid State

Abstract

Abstract The complex permittivity of the following neat liquids has been measured in the frequency range from 20 MHz to 36 GHz at 20°C: (1) 2‐pyrrolidinone, (2) N‐methyl‐, (3) N‐vinyl‐, (4) N‐ethyl‐, (5) N‐cyclohexyl‐, (6) N‐benzyl‐2‐pyrrolidinone, (7) N‐methyl‐2‐piperidone and (8) N‐methyl‐caprolactam. The results can be described by one or two superimposed Debye‐type components. One component is due to rotational tumbling of single molecules. The additional component is ascribed to associates, possibly dimers, in the case of (1), but in the other cases, as far as occuring to a significant extent, that is with (4) to (8), to intramolecular motions.