Nuclear Magnetic Resonance Spectroscopy. Conformational Equilibria and Equilibration of 4,4-Difluorocyclohexanone and 6,6-Difluoro-cis-decal-2-ones

The rates of ring inversion and conformational equilibration of 6,6-difluoro-cis-decal-2-one and 10-methyl-6,6-difluoro-cis-decal-2-one have been determined using fluorine magnetic resonance spectroscopy. The activation energies were found to be 11.3 ± 0.3 and 9.5 ± 0.1 kcal/mol, respectively. 4,4-Difluorocyclohexanone, however, appears to exchange its fluorines between conformationally nonequivalent sites rapidly on the nmr time scale even at -180º.