Nuclear Magnetic Resonance Spectroscopy. Conformational Equilibria and Equilibration of 5,5-Difluoro-cis-hydrindan and 9-Methyl-5,5- difluoro-cis-hydrindan

The rate of ring inversion and conformational equilibration of 5,5-difluoro-cis-hydrindahn as been determined from the temperature dependence of its fluorine magnetic resonance spectrum. The activation energy for ring inversion was found to be 6.9 ± 0.2 kcal/mol. Introduction of an angular methyl group at the 9 position resulted in an increase in the activation energy to 8.1 ± 0.3 kcal/mol