title: Multiwavelength spectrophotometric determination of acidity constants of some azo dyes.
abstract: A multiwavelength spectrophotometric titration method was applied to study the acidity constants of some azo dyes in water. The UV-vis absorption spectra of azo dye solutions were recorded in the course of their pH-metric titration with a standard base solution. The protolytic equilibrium constants, spectral profiles, concentration diagrams and also the number of components have been calculated. The quantitative effects of the substituents on the acidity of the studied azo dyes were investigated by the linear free energy relationship (LFER) using Hammet sigma constant (sigma) and field and resonance effects of Kamlet and Taft (f and Re, respectively).
authors: Department of Chemistry, Razi University, Kermanshah, Iran. mshamsipur@yahoo.com
authors: Mojtaba
authors: M
authors: Shamsipur
authors: Bozorgmehr
authors: B
authors: Maddah
authors: Bahram
authors: B
authors: Hemmateenejad
authors: Shohreh
authors: S
authors: Rouhani
authors: Kamaladin
authors: K
authors: Haghbeen
authors: Kamal
authors: K
authors: Alizadeh
mesh_terms: D000465:Algorithms; D001391:Azo Compounds / Q000032:analysis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D013053:Spectrophotometry / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry
chemical_list: D001391:Azo Compounds; D014867:Water