Daniela Ivón Fernández Ayala. Sexto Semestre. QFB. Ataque Nucleofílico. likes · 28 talking about this. Personal Blog. A partir de nuestros resultados, se encontró que un ataque electrofílico permite un ataque nucleofílico, entonces es necesario un segundo ataque mediante.

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In order to observe systematically how the pyridine nitrogen atom acquires electrophilic character and analyze the proposals made by Gibson et al.

Nucleófilo – Wikipedia, a enciclopedia libre

If we consider that the nucleophilic substitution on tartrazine is carried out in an aqueous system and at acid pH values. The results indicate that the solvation process modifies the reactivity descriptors values.

The six electron donor 2,6-bis imino pyridines 1 are tridentate ligands with potentially reactive nitrogen and carbon atoms Figure 1 [4, 5]. Drugs14 Cancer15 A38, Phosphorus esters are known to be quite reactive. SCE is accessible to biological reductors such as cysteine, gluthatione and ascorbic acid. The condensed form of the Fukui function for an atom k in a molecule can be expressed as: The energy values of the ionic states of tartrazine, cation and anion, were calculated by using the geometry of the neutral system.

Moreover, the bond distances were very similar to those reported in the literature [26].

This suggests the loss of an ethyl group C 2 H 5 from the original complex. These ACs have been used in large amounts as dyes because they may be obtained from relatively inexpensive methods. Services on Demand Journal.


II ; Francisco C. How to cite this article. Health C18 The optimized structure, in aqueous phase, is depicted in Figure 2b.

Halogenación de alquenos – Wikipedia, la enciclopedia libre

New York,p. A more detailed electrochemical investigation is being carried out.

Stewart Computational Chemistry, Colorado Springs. The Fukui function can be written as [28]: Since 5ac has no ortho substitution in the N -phenyl ring, the nucleophilic attack at the pyridine nitrogen atom does not depend on steric factors. Introduction The relevance of nitric oxide and therefore of the nitric oxide synthase enzymes NOS in biological processes is now widely recognized. If tartrazine is subject to an electrophilic attack, then a cleavage of the azo bond is expected, Figure 4a.

Halogenación de alquenos

They reported a vibrational Raman characterization of this dye at different pH values [26]. In the present work DFT reactivity descriptors for tartrazine were calculated employing DFT theory in the gas and aqueous phases. Chemospherenucldofilico 12 From last results is possible to nuc,eofilico that an electrophilic attack to tartrazine may cause the cleavage of the azo bond.

Tartrazine has been scarcely studied from a theoretical point of view [26, 27]. In order to evaluate the reactivity at atomic resolution, the Fukui Function was evaluated through equations O aduto formado pode ser separado do excesso do reagente por CCF, e quantificado por fluorimetria.


Even while 7 is stable for extended periods at room temperature, the ligand was easily deprotonated at the imine methyl group with loss of methane [7, 25]. Conclusions In the present work DFT reactivity descriptors for tartrazine were calculated employing DFT theory in the gas and aqueous phases. Also, a very minor effect has been noted in its degradation process due to the temperature variation [19].

The local HSAB principle and the DFT local descriptors suggest that nucleophilic attack at the pyridine nitrogen atom of 2,6-bis imino pyridines 1 depends fundamentally nucleofiilico stereoelectronic rather than on steric factors. Barranca del Muerto No.


In this sense, an evaluation of the reactivity exhibited by tartrazine at the molecular level may become fundamental to develop new and better methods to degrade tartrazine in aqueous conditions. The local HSAB principle has been widely used in studies on multiple reaction sites and in strong and weak chemical interactions [].

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 [26].

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