CONFORMATION OF 2,3-DICYANO-2,3-DIMETHYLBUTANE BY ELECTRIC DIPOLE MOMENT AND KERR EFFECT MEASUREMENTS

Dipole moment and molar Kerr constant (x 1012) values at 25° are recorded for 2,3-dicyano-2,3-dimethylbutane as a solute in carbon tetrachloride (2.13 D, + 61). The electric moments have also been determined at 45° (2.30 D) and at 7° (1.98 D). Conformational analysis shows that the results at 25° indicate an equilibrium mixture of 82% of the trans-rotamer and 18% of the gauche-rotamer of the 2,3-dicyano-2,3-dimethylbutane molecule in which the dihedral angle is 85°. The temperature-dependence of the dipole moment in carbon tetrachloride solution yields an apparent internal energy difference between the two rotational isomers of 1.31 kcal./mole.