Thermodynamic and Spectroscopic Study of Pyrrolidine. II. Vibrational Spectra and Configuration

The Raman spectrum of pyrrolidine liquid at several temperatures and the infrared spectra of pyrrolidine in the vapor, liquid, and solid states, in the 320–3500 cm—1 region and over the temperature range +150°C to —120°C have been recorded. Similar but less extensive studies were made on pyrrolidine N–D. Evidence for the presence of several configurational isomers in the liquid and solid states was obtained. A vibrational assignment, complete except for one degree of freedom, has been made and used to calculate the entropy of the ideal vapor. Comparison with the measured entropy has shown that pyrrolidine in the vapor is a free or an almost free pseudorotator.