THE CONFORMATIONAL EQUILIBRIUM OF 1,3-DICHLORO-5-METHYLCYCLOHEXANE

Article abstract of DOI:10.1016/S0040-4020(01)98859-3

Two of the stereoisomers of the title compound were prepared and their dipole moments were measured.For the r-1,c-3-dichloro-t-5-methylcyclohexane, the free energy difference between conformers with axial-axial (aa) and equatorial-equatorial (ee) chlorines was measured by a variable temperature NMR method, and the value found was 1.3+/-0.2 kcal mol^-1 (in acetone) favoring the latter.Molecular mechanics studies show that the solvation energy and the electrostatics are of major importance in understanding this equilibrium.Calculations show the effect of the methyl group is essentially additive, and give for cis-1,3-dichlorocyclohexane itself ee<*>aa ΔH +3.0 kcal mol^-1 (acetone).