Synthesis of new thiazolidin-4-one derivatives, characterization and determination of their protonation constants by potentiometric titration method

In the first stage of this work which was planned in two stages, three compounds containing thiazolidin-4-ones were synthesized and characterized. In the characterization, instrumental techniques such as IR, 1H NMR, 13C NMR and DSC were used. In the second stage, protonation constants of the compounds were determined by potentiometric titration method in %60 dioxane-%40 water media at 25 ± 0.1oC under nitrogen atmosphere and at constant ionic strength of 0.1 M. Obtained data from the titrations were evaluated by a computer programme, BEST. After that, by using potentiometric titrations values, the distribution diagrams which are indicating the changes of concentrations of the emerging species were plotted as a function of pH by using computer program SPEXY-C, which also developed by Martell-Motekaitis.As a result of the potentiometric and analytical studies, it has been observed that all the thiazolidin-4-ones ligands titrated here have two protonation constants. On the other hand, attempts to investigate the effects of the substituents on the protonation constants of the thiazolidin-4-ones were failed since the substituents are far away from the protonable parts of the molecules.