Facultad Regional Córdoba

Permanent URI for this communityhttp://48.217.138.120/handle/20.500.12272/94

Browse

Author: search.filters.author.Caglieri, SilvanaSubject: search.filters.subject.Organic synthesis

Search Results

Now showing 1 - 9 of 9
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Theoretical study of aniline acetylation catalyzed by Mn2+ ions
    (2015) Caglieri, Silvana
    Theoretical study of aniline acetylation 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 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 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 77.38 kcal/mol of energy for the tetrahedral intermediate and the energy of activation for the reaction was 23.22 kcal/mol.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Theoretical study of acetylation of ethylamine catalyzed by Zn2+ions
    (2015) Caglieri, Silvana; Macaño, Hèctor Rubèn
    A theoretical study of acetylation of ethylamine catalyzed by Zn2+ 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 Zn2+ 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 57.82 kcal/mol of energy for the tetrahedral intermediate and the energy of activation for the reaction was 9.59 kcal/mol.
  • Thumbnail Image
    Item
    Solvent effect on the aniline acetylation: Theoretical study
    (2015) Caglieri, Silvana
    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 and the nitrogen from the amine produces the nucleophilic attack on the carbonyl carbon of the anhydride to obtain tetrahedral intermediate, decisive step of the reaction rate. Subsequent loss of a proton will yield the amide and acetic acid as products. Computational investigation and an experimental work, agreed that this reaction takes place with the formation of a tetrahedral intermediate. A theoretical study of aniline acetylation in several solvents 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 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- 2 nd order Mo/ller–Plesset method. Following the same procedure it was identified the geometric parameters and energy of intermediate. The nature of solvent has an important effect on the reaction. In order to investigate the solvent effect on the aniline acetylation, both aprotic solvents such as: acetonitrile and acetone and protic solvents such as: methanol and ethanol were used. The effect of the solvent was performed with IEFPCM o PCM (Polarizable Continuum Model) method. Values of activation energy are reported in Table. Acetonitrile (aprotic solvent with the highest dielectric constant showed in the table) reveals to be the best solvent in term of activity for the reaction. This behavior could be associated with greater stability of the intermediate of the reaction.
  • Thumbnail Image
    Item
    Theoretical study of alkaline acetylation of p-methylaniline
    (2015) Caglieri, Silvana; Servetti, Gustavo
    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. The nitrogen from the amine produces the nucleophilic attack on the carbonyl carbon of the anhydride to obtain tetrahedral intermediate, decisive step of the reaction rate. Subsequent loss of a proton will yield the amide and acetic acid as products. 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 p-methylaniline 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 Density Functional Theory (DFT) 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. The Figure show the optimized structure of the intermediate and the Table lists the geometric parameters, lengths and binding angles values, obtained. The calculations show 12.80 kcal/mol of activation energy.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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.