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Información tecnológica

On-line version ISSN 0718-0764

Abstract

ENSUNCHO, Adolfo E; LOPEZ, Jesús M  and  ROBLES, Juana. Computational Study of the Kinetics and Mechanism of the Reduction of Allura Red Dye by Sodium Bisulfite in Aqueous Phase. Inf. tecnol. [online]. 2013, vol.24, n.2, pp.15-22. ISSN 0718-0764.  http://dx.doi.org/10.4067/S0718-07642013000200003.

The reduction kinetics of allura red dye (E-129, C.I. 16035) by sodium bisulfite at level B3LYP/6-31G(d) in aqueous phase was determined. This was done to evaluate a plausible mechanistic path for the reduction reaction of this important azo dye used in the food industry. The predicted rate constants (kSulf) for the sulfonation step were in good agreement with respect to experimental rate constants reported for some dyes of chemical structure similar to Allura red. On the B3LYP potential energy surface, were located five stationary points corresponding to reactants, transition states and products. The transition states for the first and second step of the reduction reaction are presented for the first time and characterized by calculations of intrinsic reaction coordinate and vibrational frequencies. The activation thermodynamic parameters indicated than the reaction was stable, endothermic and non-spontaneous.

Keywords : sodium bisulfite; red allura; reduction reaction; DFT calculations; azo dyes.

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