Carbon Acidity. 53. Kinetic and Equilibrium Acidities of Fluorinated Bicycloalkanes
Base-catalyzed tritium exchange kinetics in methanolic sodium methoxide are reported for lH-4-Y-perfluorobicyclo[2.2.1]heptanes, Y = F (1), H (2), CH3 (3), Br (4), I (5), CF3 (6), 1H-perfluorobicyclo[2.2.2]octane (7), and lH-perfluorobicyclo[2.2.1]hept-2-ene (8). The primary isotope effect for 2 is weak. Equilibrium cesium ion pair acidities are reported for compounds 1,2,3,6,7, and 8 in cyclohexylamine relative to conjugated hydrocarbon indicators. A Brønsted plot of the kinetic and equilibrium acidities has a slope close to unity and is used to assign pK values to related halogenated carbon acids. The acidities of the fluorinated bicycloalkanes can be accommodated completely by a classical field effect as modeled by Kirkwood-Westheimer calculations.
A. Streitwieser et al., "Carbon Acidity. 53. Kinetic and Equilibrium Acidities of Fluorinated Bicycloalkanes," Journal of the American Chemical Society, American Chemical Society (ACS), Jan 1976.
The definitive version is available at http://dx.doi.org/10.1021/ja00433a030
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© 1976 American Chemical Society (ACS), All rights reserved.