Determination of pKa values of benzoxa-, benzothia- and benzoselena-zolinone derivatives by capillary electrophoresis: Comparison with potentiometric titration and spectrometric data

Acidity constants of benzoxa-, benzothia- and benzoselena-zolinone derivatives were determined by capillary electrophoresis, potentiometry and spectrophotometry experiments. These three analytical techniques gave pKa results that were in good agreement. A convenient, accurate and precise method for the determination of pKa was developed to measure changes in acidity constants induced by heteroatom or 6-benzoyl substituted derivatives. pKa values were determined simultaneously for two compounds characterized by different electrophoretic mobility (μe) and pKa value and in the presence of an analogous neutral marker.