Now showing 1 - 9 of 9
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Experimental Analyses Emphasize the Stability of the Meisenheimer Complex in a SNAr Reaction Toward Trends in Reaction Pathways

2020 , CAMPODONICO GALDAMES, PAOLA ROSSANA , OLIVARES, MARIA BELEN , Ricardo A. Tapia

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How the Nature of an Alpha-Nucleophile Determines a Brønsted Type-Plot and Its Reaction Pathways. An Experimental Study

2022 , CAMPODONICO GALDAMES, PAOLA ROSSANA , Ricardo A. Tapia , Cristian Suárez-Rozas

The reactions between 2-chloro-5-nitro pyrimidine with a serie of α-nucleophile derivatives were kinetically evaluated. The kinetic study was carried out in aqueous media and the data shown an unusual split on the Brønsted type-plot, opening a controversial discussion based on reactivities and possible reaction pathways. These split Brønsted type-plots are discussed over the hypothetical transition state (TS) structures associated to concerted or stepwise mechanisms with emphasis on hydrogen bond interactions between electrophile/nucleophile pair able to determine the reactivities and the plausible reaction routes.

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Iso-solvation effects in mixtures of ionic liquids on the kinetics of a model SNAr reaction

2017 , J. Alarcón-Espósito , R. Contreras , CAMPODONICO GALDAMES, PAOLA ROSSANA

The SNAr reaction between 1-chloro-2,4-dinitrobenzene and morpholine was used as a model system to study solvation effects in a series of mixtures involving imidazolium based ionic liquids.

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Surfactant-mediated enzymatic superactivity in water/ionic liquid mixtures, evaluated on a model hydrolytic reaction catalyzed by alpha-chymotrypsin

2019 , C. Calderón , R. Contreras , CAMPODONICO GALDAMES, PAOLA ROSSANA

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Solvent effect on a model SNAr reaction in ionic liquid/water mixtures at different compositions

2018 , Bruno Sánchez , Cristian Calderón , Constanza Garrido , Renato Contreras , CAMPODONICO GALDAMES, PAOLA ROSSANA

A biphasic behavior observed on the reaction rate of a model SNAr reaction in ionic liquid/water mixtures was explained by preferential solvation effects in water rich mixtures, and an anion effect in mixtures with high ionic liquid content.

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Effect of the nature of the nucleophile and solvent on an SNAr reaction

2018 , Marcela Gazitúa , Ricardo A. Tapia , Renato Contreras , CAMPODONICO GALDAMES, PAOLA ROSSANA

The reaction of 2,4-dinitrobenzenesulfonyl chloride toward propylamine was kinetically evaluated in 19 organic solvents and 10 ionic liquids as reaction media.

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Kinetics and Reaction Mechanism of Biothiols Involved in SNAr Reactions: An Experimental Study

2022 , CAMPODONICO GALDAMES, PAOLA ROSSANA , Jazmín Alarcón-Espósito , OLIVARES, MARIA BELEN

Few kinetic parameters, or reaction rates, are known up to date in detail about 1-chloro and 1-fluoro-2,4-dinitrobenzene (ClDNB and FDNB, respectively) with a series of biothiols in aqueous media. These biological nucleophiles with thiol groups have been widely used as a reference in nucleophile reactivity assays due to their prevalence and cellular abundance. The main aim of this study was to elucidate the reaction mechanism based on Brönsted-type plots and reactivity patterns of the electrophile/nucleophile pairs. A complete kinetic study was performed in terms of the comparison of Brönsted-type slope parameters (βnuc) for the reactions and was used for assigning the mechanism and the rate-determining step associated with the reaction route. A mass spectrometry analysis demonstrated that the nucleophilic center of the biothiols is the -SH group and there is only one kinetic product. The kinetic study suggests that the reaction mechanism might be the borderline between concerted and stepwise pathways. An amine–enol equilibrium for the most reactive nucleophiles appears to be the main determining factor controlling the nucleophilic attack in the nucleophilic aromatic substitution reactions investigated, highlighting the anionic form for these nucleophiles. This amine–enol equilibrium involves a hydrogen bond which stabilizes the intermediate species in the reaction pathway. Thus, intramolecular bonds are formed and enhance the nucleophilic strength through the contribution of the solvent surrounding the electrophile/nucleophile pairs. Finally, we highlight the importance of the formation of electrophile/nucleophile adducts that could modify structures and/or functions of biological systems with potential toxic effects. Therefore, it is essential to know all these kinetic and reactivity patterns and their incidence on other studies.

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Mechanism for the SNAr reaction of atrazine with endogenous thiols: experimental and theoretical study

2017 , K. Calfumán , S. Gallardo-Fuentes , R. Contreras , R. A. Tapia , CAMPODONICO GALDAMES, PAOLA ROSSANA

The mechanism for the SNAr reaction of atrazine with endogenous thiols: a stepwise or concerted process?

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Self-Sustaining Supramolecular Ionic Liquid Gels for Dye Adsorption

2018 , Carla Rizzo , Salvatore Marullo , CAMPODONICO GALDAMES, PAOLA ROSSANA , Ivana Pibiri , Nadka Tz. Dintcheva , Renato Noto , Daniela Millan , Francesca D’Anna