Microwave Spectrum, Conformation, Dipole Moment, and Barrier to Internal Rotation in Methyl Vinyl Ether

Abstract

The microwave spectrum of methyl vinyl ether, CH3OCH=CH2, has been studied in the frequency region 8 to 40 Gc/sec. Absorption lines have been assigned to a planar cis isomer, with a barrier to internal rotation of the methyl group of 3830 ± 100 cal/mole. The components of the dipole moment along the principal axes of inertia were measured and found to be μa = 0.294 D, μb = 0.915 D (μ total = 0.96 D). Spectra were observed of the excited methyl torsional state and of two additional excited vibrational states, corresponding, respectively, to vibrations at about 240, 205, and 327 cm−1. These findings are confirmed by far-infrared and Raman spectra.