Dielektrische Messungen an polaren Gemischen. 6. Mitteilung Harnstoffe

The dielectric increments of substituted ureas in polar solvents are measured. The dipole moments and the correlation parameters are calculated and discussed. It is shown that the results are only explainable if cis‐conformation of the alkyl substituent to the carbonyl group and a hydrogen bridge to the solvent are assumed. The frequency dependence of some solutions is measured and the relaxation times are calculated. It is possible to construct COLE‐arc‐plots for the solute from the real and the imaginary part of the increment. Measurements of the temperature dependence of the dielectric constant of tetraethyl‐urea shows the normal behaviour of a liquid without hydrogen bridges and without free rotation in the solid.