INTERNAL-ROTATION IN ISOPROPYL-ALCOHOL STUDIED BY MICROWAVE SPECTROSCOPY

The microwave spectrum of isopropyl alcohol was reinvestigated in much more detail than in a previous paper. The trans spectra were analyzed in terms of a rigid-rotor model modified by first-order centrifugal distortion effects. For the gauche form, the spectra of which were complicated by a tunneling effect between the two equivalent minima, the b-type and c-type transitions in both the symmetric and antisymmetric sublevels were observed in addition to a-type ones which occurred between the symmetric and antisymmetric levels. The observed transition frequencies were analyzed by using an effective 2 × 2 Hamiltonian. The tunneling splitting was determined to be 46798.50 ± 0.11 (±σ) MHz. An analysis of the Stark effects gave |〈s|μa|a〉| = 1.114 ± 0.015 D, μb = 0.737 ± 0.025 D, and μc = 0.8129 ± 0.0049 (±σ) D. The trans spectra of (CH3)2CHOD were analyzed similarly to those of the normal species, but a definite assignment could not be made for the gauche form. © 1979 American Chemical Society.