Thermodynamic and Spectroscopic Study of Pyrrolidine. I. Thermodynamic Properties in the Solid, Liquid, and Vapor States

Abstract

The low‐temperature heat capacity, heat of combustion, heat of vaporization, and vapor pressure of pyrrolidine have been measured. Information obtained from these measurements is as follows: the heat capacity of the solid from 14 to 215°K; the liquid heat capacity from 215 to 312°K; a heat of transition of 127 cal mole^—1 at 207.14°K; a heat of fusion of 2053 cal mole^—1 at the melting point, 215.31°K; the entropy of the liquid at 298.15°K, 48.78 cal mole^—1 deg^—1; the standard heat of formation from the elements at 298.15°K, —9.81 kcal mole^—1; the heat of vaporization at 298.15°K, 8990 cal mole^—1; and the vapor pressure, log₁₀P(mm) = 6.88816 — 1157.40/(t+202.332). From a comparison of the calorimetric entropy of the ideal gas with statistically calculated values based upon newly obtained spectroscopic data, pyrrolidine vapor appears to have the indefinitely puckered cyclopentane type structure. Thermodynamic properties of the solid, liquid, and ideal gas have been tabulated at selected temperatures.