THE BARRIER TO INTERCONVERSION OF CYCLOHEXENE

The interconversion process between twisted conformations of cyclohexene via a bent intermediate form is reexamined utilizing previously published far-infrared data along with molecular mechanics (MM3) calculations. This process is treated as a periodic one-dimensional hindered pseudorotation, and it is demonstrated that the anharmonicity in the vibrational data is compatible with a barrier to interconversion in the 8.4-12.1-kcal/mol range. This range is higher than the MM3 value of 7.22 kcal/mol or published values from ab initio calculations.