The Kerr constants of 4‐and 5‐phenyl‐1,3‐dioxanes and the conformations of their phenyl groups

The molar Kerr constants and the dipole moments of r-2-cis-5-dimethyl-trans-5-o-1,3-dioxane (1), r;-2-trans-5-dimethyl-cis-5-o-1,3-dioxane (2), 2-methyl-5,5-di-o-1,3-dioxane (3), cis-2-methyl-4-o-1,3-dioxane (4)-2-cis-6-dimethyl-cis-4-o-1,3-dioxane (5), r-2-cis-6-dimethyl-trans-4-o-1,3-dioxane (6) have been obtained in CCl4 at 20°C. The molecular anisotropy of 3, evaluated from the light-scattered measurements, has also been obtained. The rotation angles of the phenyl groups with respect to the Csp2-C-H plane or the Csp2-C-CH3 plane have been determined by the comparison of the observed molar Kerr constants with those calculated for various conformations; these values emerge as (2): 60°; (3): o-eq. 70°, o-ax. 15° or o-eq.80°, o-ax.−10°; (4) and (5): 25°; (6): 60° (turning towards the oxygen atom of the dioxane cycle).