Facultad Regional Córdoba
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Item Theoretical study of acid acetylation of aniline(2014) Caglieri, Silvana; Servetti, Gustavo Iván; Picco, EduardoThe 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.Item Theoretical Study on Amines: aniline, N-methylaniline, p-methylaniline and pmethyl-N-methylaniline(2024) Caglieri, Silvana; Servetti, Gustavo Iván; Picco, EduardoThe 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.