ピリジルアゾフェノール系試薬のバナジウム(V), ニッケル(II)及び鉄(II)キレートの安定度定数

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Acid dissociation constants of 2-(2-pyridylazo)phenol (PAP) and 2-(2-pyridylazo)-5-methylphenol (PAP-5Me) and the stability constants of their chelates with vanadium (V), nickel (II), and iron (II) were determined by spectrophotometry at 293K and μ=0.1. The acid dissociation constants were ; pK_a1 (PAP) =2.53,pK_a2 (PAP)=8.76,pK_a1 (PAP-5Me)=2.67 and pK_a2 (PAP-5Me)=8.95. Since iron (II)-PAP chelate was insoluble in water, its stability constant in water was determined by an extrapolation of stability constants in aqueous dioxane. Other stability constants were determined directly in water. They were ; logβ_1,{V(V)-PAP}=12.43,logβ_1 {Ni(II)-PAP}=9.79,logβ_2 {Ni(II)-PAP}=21.78,logβ_1 {Fe(II)-PAP}=11.95,logβ_2 {Fe(II)-PAP}=24.45,logβ_1 {V(V)-PAP-5Me}=12.87,logβ_1 {Ni(II)-PAP-5Me}=10.67,logβ_2 {Ni(II)-PAP-5Me}=22.17,logβ_2 {Fe(II)-PAP-5Me}=25.51.
社団法人日本分析化学会の論文
1991-02-05