Изучение кислотно-основных свойств и структурных параметров тиобарбитуровой кислоты

Abstract

The stepwise proton-ligand stability constant of thiobarbituric acid anion was determined in an aqueous solution via pH-potentiometry at ionic strength I=0,1 and temperature T=20°C. Based on the absorption spectra analysis of thiobarbituric acid (H[2]L, H[2]thioBar) solutions in the UV-region at different pH values, it was shown that H[2]thioBar could exist in di-, mono-, and deprotonated forms. This latter fact is reflected in the particle yield H[2]L diagrams as a function of the aqueous solution pH. Besides, some geometric and physico-chemical characteristics of H2thioBar were described by means of quantum chemical calculations.