Measurement of 4-(2-thiazole azo) rososinol acidy constants by means of ultraviolet spectroscopy and chemometrics in water-acetonitrile and water-dioxane binary mixtures

Abstract

In this paper, by combining ultraviolet spectroscopy and Chemometrics method, the acid dissociation constant of 4- (2-thiazole azo) rososinol was measured. The absorption spectra of the 4- (2-thiazole azo) rososinol solution have a large spectral overlap, so it will be difficult to determine its acid dissociation constant using conventional spectroscopy. Using ultraviolet-visible spectroscopy and two rank annihilation factor analysis (TRAFA), acid constants, number of species, molar fraction, relative standard deviation (RSD) and net species spectrum acid dissociation of 4- (2-thiazole azo) rososinol in 20 to 80% v/v of acetonitrile in water and dioxane in water was calculated. The results obtained by the two rank annihilation factor analysis method show the efficiency of this method in determining the solution with high spectral overlap. As the percentage of solvents increases, the acid constant becomes smaller, which can be explained by the fact that the solubility and dielectric constant of water, acetonitrile and dioxane are different. The value of these variables depends on the physical parameters (dielectric constant and induction number).

Keywords

• ‎4- (2-thiazole azo) rososinol ‎
• ultraviolet spectroscopy ‎
• two rank annihilation factor analysis ‎
• acid dissociation constant