Ionization Constants of the Six Dichloroanilines and the Six Dichlorophenols in Aqueous Solution at 25 °C

The thermodynamic ionization constants of the six dichloroanilines and the six dichlorophenols in aqueous solution at 25 °C have been determined by the spectrophotometric method. The pK values found are recorded in table 3. An approximately linear relation is found to exist between the pK value of a dichloroaniline and the pK value of the corresponding dichlorophenol. The relation is This equation yields pK values which differ from the observed by not more than 0.06 pK unit and, on the average, by 0.03 pK unit; it applies even when both substituents are in the ortho position.