Browsing by Author "Servetti, Gustavo Iván"

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    Proyecto - Quìmica orgànica computacional: Estudio teòricode acilaciòn de aminas
    (2015) Caglieri, Silvana; Macaño, Hèctor Rubèn; Servetti, Gustavo Iván; Pagnan, Mariángeles; Zanel, Pamela; Serra, Vanina; Di Paola, Milagros
    El estudio de la acilación de aminas es de gran interés por la utilidad de sus productos de reacción dentro de la industria química y porque constituye una de las transformaciones más usadas en síntesis orgánica, ya que proporciona un medio eficiente y económico para la protección de grupos amino en un proceso sintético. La acilación de una amina es una reacción de sustitución nucleofílica sobre carbono insaturado, siendo el nucleófilo la propia amina. Se han llevado a cabo estudios teóricos (Tong et.al, 2012) y trabajos experimentales (Naik et al., 2004) sobre esta reacción y coinciden en que la misma transcurre a través de la formación de un intermediario tetraédrico. El objetivo de este proyecto consiste en estudiar la acilación de diferentes aminas alifáticas y aromáticas, estableciendo un orden de reactividad de las mismas frente a dicha reacción, empleando como herramienta la química teórica computacional y comparando los resultados teóricos con datos experimentales. El estudio teórico se lleva a cabo empleando el programa Gaussian´09 - Gauss View 5.0. y los siguientes métodos de estructura electrónica: DFT/B3LYP base 3-21G* y base 6-31G*; MP2 y AM1, mediante los cuales se optimizan las geometrías y estructuras de todos los compuestos orgánicos que intervienen en la acilación, a saber: aminas y anhídrido acético (reactivos) y ácido acético y amidas (productos), incluyendo el cálculo de las correspondientes energías. Además se diseñan y modelan las geometrías y las estructuras de los intermediarios de reacción de cada acilación, incluyendo el cálculo de las correspondientes energías. Como complemento del estudio teórico se lleva a cabo en el laboratorio de CIQA la acilación de las siguientes aminas: propilamina, hexilamina, isopropilamina, anilina y difenilamina. Los reactivos y productos se analizan y cuantifican en un cromatógrafo gaseoso y los resultados se expresan en conversión mol%. El orden de reactividad reportado por el estudio teórico coincide con los resultados experimentales. La propilamina presenta la mayor reactividad frente a la acilación en comparación con las demás aminas alifáticas y con respecto a las aminas aromáticas, la anilina muestra una mayor conversión en comparación con la difenilamina.
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    Theoretical study of acetylation of ethilamine catalyzed by Co2+ions
    (2016) Caglieri, Silvana; Servetti, Gustavo Iván
    Theoretical study of acetylation of ethylamine catalyzed by Co2+ ions from the analysis of intermediate of the reaction was carried out. The study of acetylation of amines is of great interest by the utility of its products of reaction and is one of the most frequently used transformations in organic synthesis as it provides an efficient and inexpensive means for protecting amino groups in a multistep synthetic process. Acetylation of amine is a nucleophilic substitution reaction. This reaction can be catalyzed by Lewis acid1 , metallic ion. In reaction mechanism, the metallic ion formed a complex with the oxygen of the acetic anhydride carbonyl, facilitating the polarization of the same and the successive addition of amine at the position to form a tetrahedral intermediate, determining step of the rate of the reaction. Experimental work2 agreed that this reaction takes place with the formation of a tetrahedral intermediate. In the present theoretical work were investigated the structure and energy of the tetrahedral intermediate of the reaction catalyzed by Co2+ ions. Geometries of all species involved in the acetylation were made and identified. All of the geometry optimizations were performed by the method at the DFT/B3LYP level of theory and the method MP2. Were adopted the 6-31+G* basis sets. Energies were calculated using DFT, MP2 and the Mechanics-UFF method. Following the same procedure it was identified the geometric parameters and energy of reaction intermediate.
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    Theoretical study of acetylation of ethylamine catalyzed by Mn2+ions
    (2015) Caglieri, Silvana; Servetti, Gustavo Iván
    A theoretical study of acetylation of ethylamine catalyzed by Mn2+ ions from the analysis of intermediate of the reaction was carried out. The study of acetylation of amines is of great interest by the utility of its products of reaction and is one of the most frequently used transformations in organic synthesis as it provides an efficient and inexpensive means for protecting amino groups in a multistep synthetic process Acetylation of amine is a nucleophilic substitution reaction. This reaction can be catalyzed by Lewis acid, metallic ion. In reaction mechanism, the metallic ion formed a complex with the oxygen of the acetic anhydride carbonyl, facilitating the polarization of the same and the successive addition of amine at the position to form a tetrahedral intermediate, determining step of the rate of the reaction. In the present theoretical work were investigated the structure and energy of the tetrahedral intermediate of the reaction catalyzed by Mn2+ ions. Geometries of all species involved in the acetylation were made and identified. All of the geometry optimizations were performed by the method at the DFT/B3LYP level of theory and the method MP2. Were adopted the 6-31+G* basis sets. Energies were calculated using the Mechanics-UFF method. Following the same procedure it was identified the geometric parameters and energy of reaction intermediate. The calculations show 66.42 kcal/mol of energy for the tetrahedral intermediate and the energy of activation for the reaction was 17.45 kcal/mol.
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    Theoretical study of acetylation of p-methylaniline catalyzed by Ni2+ ions
    (2017) Caglieri, Silvana; Macaño, Hèctor Rubèn; Servetti, Gustavo Iván
    A theoretical study of acetylation of p-methylaniline catalyzed by Ni2+ ions from the analysis of intermediate of the reaction was carried out. The study of acetylation of amines is of great interest by the utility of its products of reaction and is one of the most frequently used transformations in organic synthesis as it provides an efficient and inexpensive means for protecting amino groups in a multistep synthetic process. Acetylation of amine is a nucleophilic substitution reaction. This reaction can be catalyzed by Lewis acid1 , metallic ion. The reaction and the compounds studied are shown in Figure1. + + H3C O OH O O O H3C CH3 H3C NH2 Ni 2+ H3C O NH Fig. 1: General Scheme of Acetylation In reaction mechanism, the metallic ion formed a complex with the oxygen of the acetic anhydride carbonyl, facilitating the polarization of the same and the successive addition of amine at the position to form a tetrahedral intermediate, determining step of the rate of the reaction. Experimental work2 agreed that this reaction takes place with the formation of a tetrahedral intermediate. In the present theoretical work were investigated the structure and energy of the tetrahedral intermediate of the reaction catalyzed by Ni2+ ions. Geometries of all species involved in the acetylation were made and identified. All of the geometry optimizations were performed by the method at the DFT/B3LYP level of theory and was adopted the 6-31+G* basis set. Energies were calculated using the Mechanics-UFF method. Following the same procedure it was identified the geometric parameters and energy of reaction intermediate. The calculations show 61.89 kcal/mol of energy for the tetrahedral intermediate and the energy of activation for the reaction was 16.05 kcal/mol.
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    Theoretical study of acid acetylation of aniline
    (2014) Caglieri, Silvana; Servetti, Gustavo Iván; Picco, Eduardo
    The acetylation of amines is one of the most frequently used transformations in organic synthesis as it provides an efficient and inexpensive means for protecting amino groups in a multistep synthetic process. Acetylation of amine is a nucleophilic substitution reaction. This reaction can be catalyzed by Brönsted acid. In the mechanism, the acetic anhydride first accepts a proton at the carbonyl oxygen and this change enhances the positive charge on the carbonyl carbon. This protonation facilitates the successive addition of amine at the position to form a tetrahedral intermediate, determining step of the rate of the reaction. Computational method to study the reaction using acid catalysis [1] and an experimental work [2], agreed that this reaction takes place with the formation of a tetrahedral intermediate. A theoretical study of acid acetylation of aniline from the analysis of intermediate of the reaction was carried out. Geometries of all species involved in the acetylation were made and identified. All of the geometry optimizations were performed by the method at the DFT - Density Functional Theory [3] with B3LYP level of theory and was adopted the 6-31G* basis set. Energies of all reagents and products and the energy of activation for the reaction were calculated using the MP2- 2nd order Mo/ller–Plesset method. Following the same procedure it was identified the geometric parameters and energy of intermediate. Figure 1 show the optimized structure of the intermediate and the Table 1 lists the geometric parameters, lengths and binding angles values, obtained. The calculations show 18.37 kcal/mol of activation energy.
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    Theoretical study of alkaline acetylation of diphenylamine
    (2016) Caglieri, Silvana; Macaño, Hèctor Rubèn; Servetti, Gustavo Iván
    The acetylation of amines is one of the most frequently used transformations in organic synthesis as it provides an efficient and inexpensive means for protecting amino groups in a multistep synthetic process and the amide bond is found to be present in a large number of pharmacologically active molecules. Acetylation of amine is a nucleophilic substitution reaction. This reaction is carried out with acetic anhydride in the presence of amine bases such as tertiary amine and pyridine. Computational investigation1 and an experimental work2 , agreed that this reaction takes place with the formation of a tetrahedral intermediate. A theoretical study of alkaline acetylation of diphenylamine from the analysis of intermediate of the reaction was carried out. Geometries of all species involved in the acetylation were made and identified. Energies of all reagents and products and the energy of activation for the reaction were calculated using the method DFT - Density Functional Theory with B3LYP level of theory and was adopted the 6-31+G* basis set. Following the same procedure it was identified the geometric parameters and energy of intermediate. All the calculations were executed using Gaussian 09 software package. The calculations show 18.01 kcal/mol of activation energy.
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    Theoretical Study on Amines: aniline, N-methylaniline, p-methylaniline and pmethyl-N-methylaniline
    (2024) Caglieri, Silvana; Servetti, Gustavo Iván; Picco, Eduardo
    The acetylation of amines is one of the most frequently used transformations in organic synthesis as it provides an efficient and inexpensive means for protecting amino groups in a multistep synthetic process. Geometric parameters of reactants: aniline,N-methylaniline,p-methylaniline1 and p-methyl-N-methylaniline were performed in the gas phase using the DFT/B3LYP density functional quantum mechanical method and was adopted the 3-21+G* basis set. Enthalpies of formation were determined using the AM1 method. The table lists the energies, lengths and angles values obtained. Steric effects caused by the additional methyl group might be responsible of an increase of the energy of N-methylaniline compared to aniline and an increase of the energy of p-methyl-N-methylaniline compared to p-methylaniline.