CHARACTERIZATION OF THE IONIZATION AND SPECTRAL PROPERTIES OF MERCAPTO-CARBOXYLIC ACIDS - CORRELATION WITH SUBSTITUENTS AND STRUCTURAL FEATURES

The ionization constants in aqueous solutions of meso and DL-dimercapt osuccinic acid and of monomethyl and dimethyl meso-succinates were car efully determined by potentiometric and spectrophotometric methods as a result of the increasing interest in these molecules as heavy metal chelators. In order to explain the influence of various substituents o n ionization and C-13 NMR properties, the study was extended to the re lated oxygen derivatives of succinic acid and to simpler ethanoic deri vatives. With the Swain-Lupton dual substituent treatment it was possi ble to clarify the influence of substituents on both spectral and equi librium parameters. The differences in pK due to conformation are also discussed.