title: Formation rates and protonation constants of azo dyes in a sodium dodecylsulphate micellar solution.
abstract: The effects of a sodium dodecylsulphate micellar solution on the coupling rates of several diazotizated arylamines with N-(1-naphthyl)-ethylenediamine and the shifts in the protonation constants of the corresponding azo dyes are quantitatively studied. Aniline, o-, m- and p-aminobenzoic acids, ethyl p-aminobenzoate and several sulphadrugs are used, and the relationships among the intensity of the effects and the molecular structure of the diazonium ions and the dyes are discussed. A single simplified procedure for the determination of all the substances at pH = 1.3 +/- 0.3, where coupling is quickly completed to directly produce the protonated form of the dyes, is established and applied to the analysis of several pharmaceutical preparations.
authors.affiliation: Departamento de Química Analítica, Facultad de Química, Universitat de Valencia, 46100 Burjassot, Valencia, Spain.
authors.forename: J S
authors.initials: JS
authors.lastname: Romero
authors.forename: M C
authors.initials: MC
authors.lastname: Alvarez-Coque
authors.forename: G R
authors.initials: GR
authors.lastname: Ramos