Development of a Robust Protocol for the Determination of Weak Acids’ pK_a Values in DMSO

Abstract

Two methods for the determination of pK a values of weak acids are described, a direct titration with dimsyl potassium in the presence of an indicator and a back-titration in which an analyte/indicator mixture is deprotonated and then titrated with ammonium chloride. Both methods have been validated by measuring pK a values of compounds, for which values had been determined previously. The back-titration method was applied to measure pK a values of two 1,3-dithiane-derived bissulfoxides and a monosulfone.