Study of the acid-base properties of quercetin in aqueous solutions by color measurements

Acid-base properties of quercetin in aqueous solutions are studied by the method chemical color measurements and dissociation constants (pK) are determined. The pK values are assigned to corresponding functional groups of quercetin and a probable scheme of their dissociation is proposed. A diagram of the distribution of ion-molecular forms of quercetin in the pH range 1-13 is built.