Thermodynamic and kinetic properties of trans-3,4,5,6-tetramethyl-9, 10-dihydroxy-9,10-dihydrophenanthrene: pseudo-rotational barriers around biphenyl axis.
The thermodynamic and kinetic properties of trans-3,4,5, 6-tetramethyl-9,10-dihydro-9,10-dihydroxyphenanthrene (4) and its derivatives were studied. The equilibrium ratios of two the possible conformers (4eq, 4ax) were measured in various solvents, where consistently the equatorial conformers proved to be more stable than those of the corresponding axial counterparts. The activation barriers (DeltaG) for the conformational change, 4ax-->4eq, were roughly estimated to be ca. 26 kcal mol-1 at 298 K in various solvents.
Kato
H
H
Department of Chemistry, Tokyo Institute of Technology, and CREST, Japan Science and Technology (JST), Tokyo, Japan.
Ohmori
K
K
Suzuki
K
K