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Thermodynamic and kinetic properties of trans-3,4,5,6-tetramethyl-9,10-dihydroxy-9,10-dihydrophenanthrene: Pseudo-rotational barriers around biphenyl axis

✍ Scribed by Hirohisa Kato; Ken Ohmori; Keisuke Suzuki

Publisher: John Wiley and Sons
Year: 2000
Tongue: English
Weight: 128 KB
Volume: 12
Category: Article
ISSN: 0899-0042
DOI: 10.1002/(sici)1520-636x(2000)12:5/6<548::aid-chir44>3.0.co;2-w

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✦ Synopsis

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.