Theoretical basis for the detection of general-base catalysis in the presence of predominating hydroxide catalysis.

ABSTRACT

The detection of general-base catalysis in the presence of predominating specific-base catalysis in aqueous buffer solutions is examined for various relationships between k0cat and k0OH, the bimolecular rate constants for general-base and hydroxide-ion attack. The three experimental variables that affect the detection of buffer-base catalysis are the type of buffer, conjugate-acid concentration, and ionic strength. Various buffers used in pharmaceutical kinetic studies are considered, and it is concluded that buffers with high Ka values favor detection. Additionally, high conjugate-acid concentrations and ionic strengths appear to optimize the detection of general-base catalysis.