| Abstrakt: |
The free N–H stretching vibrations of various trialkylureas, R2UR′, in dilute solutions were studied in order to resolve our questions concerning the rotational isomerism of dialkylureas. In the infrared spectrum of R2UR′, where Ris isopropyl or cyclohexyl, an additional N–H band appears on the higher-frequency side of the transN–H band. It was also observed that the larger the effective size of the R′ group on R2UR′ is, the stronger the intensity of the additional band becomes. It was concluded, in connection with the rotational isomerism of dialkylureas, that the additional band arises from a form in which the N–H group is out of the skeletal plane. |
