PROTOLYTIC AND COMPLEXING PROPERTIES OF N-(2-HYDROXYETHYL)-IMINODIPROPIONIC ACID IN AQUEOUS SOLUTION

By the method of alkalinetric titration of aqueous solutions with pH-potentiometric indication at I = 0.1 mol/dm3 (KCl/KNO3) and t = 25 ± 1°C the acid dissociation constants of functional groups in the composition of a new reagent N-(2-hydroxyethyl)iminodipropionic acid pKa0 = 2.87 ± 0.02, pKa1 = 4.00 ± 0.02 and pKa2 = 9.25 ± 0.01. The complexation of the reagent with transition metal ions was studied. It is shown that N-functionalization of iminodipropionic acid by introduction of 2-hydroxyethyl substituent leads to a significant decrease in stability of complexes with copper(II) and nickel(II) ions, with cobalt(II), zinc(II) and cadmium(II) ions the stability of complexes does not significantly increase. Relatively high stability is characterized by complexes with silver(I) ions. Based on the obtained data, assumptions about the structure of the studied complexes were made.