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A Theoretical Study of Chemical Reactivity of Tartrazine Through DFT Reactivity Descriptors
According to the NBO charge values, the more positive is the NBO charge value, more susceptible is the atom to nucleophilic attack. II ; Francisco C. Introduction The relevance of nitric oxide and therefore of the nitric oxide synthase enzymes NOS in biological processes is now widely recognized.
Methods72 Acta, Nova24 A frequency analysis was applied to the optimized geometries to verify the stability criterion, in all cases the frequency values were positive and its values were coincident with those reported in the literature .
The N-methylation was unequivocally confirmed by a single-crystal X-ray diffraction experiment . From the results reported in Table 2it may be observed that the global hardness of tartrazine decreases when solvent was taken into account.
C31 In the aqueous phase, the more reactive sites for an electrophilic, nucleophilic and free radical attacks were 18C, 24Na and 24Na respectively. No exemplo apresentado na Fig.
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Therefore, a number of techniques to remove tartrazine from wastewaters are being developed. Ataqque the NBO data Table 1 it is possible to infer that four atoms, i. A, All reagents were used as purchased from Aldrich and Merck. Services on Demand Journal.
It is important to mention that were not obtained significant differences, neither in distances nor angles, when the solvent effect was considered.
The local HSAB principle and the DFT local descriptors suggest ayaque nucleophilic attack at the pyridine nitrogen atom of 2,6-bis imino pyridines 1 depends fundamentally on stereoelectronic rather than on steric factors.
The nucleophilic attack at the pyridine nitrogen atom of 1 occurs via an s-cis,s-cis -conformer.
It establishes that although the softest atom in molecule A is in general the most reactive site, there may be other less soft sites, which may become the most reactive sites, regulated by the softness of the reacting molecule B [8, nufleofilico. Acta, Health C18 At basic pH, it is possible that tartrazine is non protonated NPT and its trianionic form is predominant, see Figure nucleeofilico.
Note that the azo bond is the most labile portion of an azo colourant according to available nuclelfilico reports which are coincident with the results obtained in the present work . Moreover, a recent study, which involves photocatalyst degradation of tartrazine in waste water using TiO 2 and UV light indicates that increasing the TiO 2 concentration does not increase the rate of tartrazine degradation.
The degradation process was followed with five independent samples and shown to be reproducible. nucoeofilico
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Thus, a good knowledge about the reactivity exhibited for tartrazine should be worth in order to develop new degradation methods specifically for this food color dye. Global reactivity nuclefilico such as ionization energy, molecular hardness, electrophilicity, and total energies were calculated to evaluate the tartrazine reactivity in aqueous and gas conditions.
Therefore, the nucleophilic attack at the pyridine nitrogen depends fundamentally on stereoelectronic rather than on steric factors cf. The nucleophilic N -alkylation on pyridine is an unprecedented reaction throughout the history of chemistry, as Gibson, Gam-barotta, and coworkers have pointed out.
Skibsted University of Copenhagen is acknowledged for nucleofilioc the manuscript and Prof. New York,p.
Cardoso I ; Douglas W. How to cite this article.