Synthesis and spectrophotometric determination of acidity constants of 2,3,4,6'-tetrahydroxy-3'-sulfoazobenzene and their use in determination of aluminum

摘要

A novel azo derivative, 2,3,4,6'-tetrahydroxy-3'-sulfoazobenzene(THSA), was synthesized by using pyrogallol. The acid dissociationconstants, or K_a values, of THSA were determined by the UV-visiblespectroscopic technique. The protonation and deprotonation behaviorsof the title molecule were studied from the super basic to the superacid region (i.e. 10 N NaOH to 98% H_2SO_4), including the pH region.A selective and sensitive UV-visible spectrophotometric method wasdevised for determination of aluminum by using this ligand. Thedeveloped method was successfully applied to an alunite mineral and topharmaceutical preparations for the determination of aluminum.