Electrostatic Effects in Ionization Equilibria: An AM1 Study of Reversed Substituent Effect in 5-Fluorobicyclo[3.3.3]undecane-1-carboxylic Acid

Abstract

Relative proton transfer enthalpies δ ∆H0 of sp and ap conformers of 5-fluorobicyclo[3.3.3]undecane-1-carboxylic acid have been calculated by the AM1 method and the results were compared with the prediction of the electrostatic theory. It is shown that the great reversed substituent effect in the sp conformer (δ ∆H0 = 32.1 kJ mol-1) is substantially overestimated largely due to sterical Baeyer strain and non-bonded interactions.