Reactividad química de los azo colorantes amarillo anaranjado y rojo allura mediante descriptores globales y la función de fukui

Abstract

In the present work local and global descriptors of the reactivity were calculated for sunset yellow and allura red to analyze its intrinsic reactivity. The computational calculations were carried out in vacuum and aqueous phase. The aqueous phase is represented by a dielectric constant of 78.5, introduced by polarizable continuum model. The results show that allura red is less susceptible to nucleophilic addition than sunset yellow, because the electrodonor substituents methyl and methoxy decrease the capability of the azo group to accept electrons. The analysis of condensed Fukui function for a nucleophilic attack and local electrophilicity index showed that the preferred direction of attack the reducing agent (bisulfite ion) occurs on C4, which was in good agreement with experimental reports.