COMPLEXATION OF SILVER (I) C 2-ETHYLIMIDAZOLE

Abstract

The acid-base properties of 2-ethylimidazole were studied by pH-metric titration (EM). Using the literature data and our own results, a number of changes in the acid-base properties (pКa) of imidazoles have been established: ethylimidazole (7,93)> imidazole (7.05)>2-phenylimidazole (6,48)>2-aminobenzimidazole (6,11)> benzimidazole (5,53)>2-phenylbenzimidazole (5,23)>2-mercaptoimidazole (2,97)>1-methyl-2-mercaptoimidazole (2,11). Method The process of complexation of silver(I) with 2-ethylimidazole in the temperature range of 273-318K was investigated using potentiometric titration using a silver electrode. It has been established that the increase in temperature does not affect the stoichiometric composition of complex particles formed in the Ag-EM-H2O system. The results obtained show that as the temperature increases, the stability constants decrease. On the basis of diagrams, the distribution of complex particles depending on the ligand concentration is shown that in System Ag-EM-H2O is mainly dominated by the bis-substituted complex, the yield of which at EM concentrations above 1·10-2 mol/l is 100%. The thermodynamic functions of the formation of 2-ethylimidazole silver complexes have been calculated. It has been established that complexation reactions are exothermic. Spontaneous occurrence of complexation reactions in the system Ag-EM-H2O contributes to a negative change in enthalpy.