MICROWAVE SPECTRUM OF N-METHYL MORPHOLINE

Abstract

The rotational spectrum of N-methyl morpholine, [FIGURE], has been investigated in the 8 to 40 GHz region. Strong lines due to $^{a}R_{01}$ transitions of the equatorial methyl conformer have been assigned, giving rotational constants (in MHz) A = 4821.153 $\pm$ 0.061, B = 2342.574 $\pm$ 0.003 and $C = 1719.453 \pm 0.003 (k = - 0.598203)$ for the ground vibrational state. The barrier to methyl torsion, calculated from both the relative intensity and the A-E splitting of the v = 1 torsional satellite spectrum, is determined as $V_{3} = 1650 \pm 200$ cal/mole. Vibrational satellites due to ring deformation modes have also been observed. The dipole moment components for the equatorial conformer are determined to be (in D) $\mu_{a} = 1.21 \pm 0.02$, $\mu_{c} = 0.10 \pm 0.03$ with $\mu_{total} = 1.21 \pm 0.02.$ No lines due to the axial methy1 conformer have been assigned.