Conformation of 2,3-dicyano-2,3-dimethylbutane by electric dipole moment and Kerr effect measurements

Abstract

Dipole moment and molar Kerr constant (×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.