Microwave spectrum,centrifugal perturbation,dipole moment,and conformation of 4-methyl-1,3-dioxane

The microwave spectrum of 4-methyl-1,3-dioxane is studied in a frequency range from 16 GHz to 40 GHz. The rotational transitions of a-, b-, and c-types with J ≤ 57 are identified. The rotational constants (MHz) A = 4802.335(2), B = 2376.163(1), C = 1738.852(1) and the quartic constants of the centrifugal distortion are found for the ground vibrational state of the molecule. The components of the dipole moment (D) μ _a = 0.73(1), μ_b = 1.32(1), μ_c = 1.36(1) and the total dipole moment μ = 2.03(1) are determined. The experimental data obtained correspond to the chair conformation of the molecule with the equatorial orientation of the methyl group.