α-Deuterium isotope effects on the ionization of weak acids

Abstract

The deuterium equilibrium isotope effect, K_H/K_D, for the ionization of acetic acid is used as an example to demonstrate that the theory of statistical thermodynamics can give an explanation of the observed trends in K_H/K_D for various weak acids. By changing the diagonal force constants of the reacting species an impression can be obtained of the origin of isotope effects in these reactions. The value of K_H/K_T is also computed and it is predicted that CT₃COOH is a weaker acid than CD₃COOH.