Effets de la nature de substituants sur les constantes d'acidité et les constantes de stabilité des complexes de quelques acides nitroso-5-barbituriques

The effects of substituents on the acidity constants and stability constants of complexes of some 5-nitrosobarbituric acids). The acidity constants of some 5-nitrosobarbituric acids (violuric acids) vary according to the degree of substitution and the nature of the substituent at the 1- and 3-positions of the pyrimidine ring. The value obtained at ionic strength 0.5 mol l^?1 made it possible to calculate the stability constants of simple complexes of divalent cations (Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Fe²⁺). Potentiometric titrations were applied.