Browsing by Author "Quijano, Silvia"
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Item Computational investigation of thermal decomposition mechanism of 5-nitro-5-R-1,3-dioxane compounds(2022-08) Ruiz, Pablo; Quijano, Silvia; Quijano, JairoThis paper features the results of the computational study of thermal decomposition reaction of 5-nitro-5-R-1,3-dioxane compounds, with R = H, Br, and CH3. Computational calculations were performed with M06-2X, MPWB1K, PBE0 and ωB97X-D functionals, and 6–311 + G(d,p) basis set in gas phase and also in solution with DMSO, at different temperatures. The kinetic and thermodynamic data obtained indicate a favoring of the reaction when the molecule presents substituent groups in position 5 and when carried out in DMSO, the stability of the molecules in their energetic components was discussed, too. For R = H two different reaction mechanisms were proposed and studied. Wiberg bond indices were obtained for the reactions studied and the results were examined in terms of bond formation and bond breaking progress as well.Item Computational study of the relative stability of some glass-ionomer cement-forming molecules(2022-10) Gaviria, Jair; Quijano, Silvia; Quijano, Jairo; Ruiz, PabloThis work is part of a larger study whose main objective was to find a series of promising molecules to be used as glass-ionomer-type materials. The project was divided into 3 successive stages; the results of the first stage have been previously published and were used to continue the study. The molecules evaluated in the second stage were constructed by adding a glycidyl methacrylate molecule to the carboxylic groups of the polyacids selected in the previous stage. The modeling was done using the density functional theory for M06-2X/6-311G(d,p). The results indicate that the addition over the carboxylic groups of the fraction of the molecule, corresponding to itaconic acid, is thermodynamically favored. The final stage was modeled with the M06 functional and consisted of obtaining basic structures of glass-ionomer-type materials, by acid–base reaction between the molecules resulting from the second stage with individual ions of Ca (2 +), Zn (2 +), or Al (+ 3). It was concluded that aluminum atoms generate more compact structures that would correlate with more resistant materials.Item Understanding the mechanism of thermal decomposition of benzoylformic acid(2023-11) Giraldo Alzate, Daniel F.; Becerra, Daniela; Quijano, Silvia; Ruiz, Pablo; Quijano, Jairo; Gaviria, JairIn this work, the thermal decomposition of benzoylformic acid was studied computationally, including the decarboxylation reaction by two different mechanisms and an additional one for the decarbonylation of the compound. The PBE functional and 6-311+G(d,p) basis set in the gas phase and the aqueous solution were used. Transition states were modeled, kinetic and thermodynamic parameters were calculated for each reaction, and bonds evolution were tracked along the reaction coordinate by analysis of Wiberg bond indices. Two-step decarboxylation mechanism, initially proposed for the decomposition of pyruvic acid was found to be a probable mechanism for benzoylformic acid in gas phase, compared to the one-step decarboxylation and decarbonylation reaction.