Banca de DEFESA: LUIZ HENRIQUE MEDEIROS DA COSTA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : LUIZ HENRIQUE MEDEIROS DA COSTA
DATA : 25/02/2019
HORA: 14:00
LOCAL: a definir
TÍTULO:

REGIOSELECTIVITY OF THE N-/O-NITROSO-ALDOL REACTIONS: a DFT study of the reactions of nitrobenzene with morpholine and pyrrolidine

PALAVRAS-CHAVES:

Density Functional Theory. Nitroso-Aldol. Regioselectivity

PÁGINAS: 85
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Química Teórica
RESUMO:

Aromatic C-nitroso compounds have been widely studied because of their versatility. Investigations of these compounds can be found in several areas of scientific knowledge. The nitroso group (R-NO) acts ambivalently, that is, as nucleophile and electrophile, reacting with biomolecules that have sulfur atoms (nucleophile), for example. Aldo N-/O-Nitroso reactions have been explored, in particular, using nitrosobenzene (PhNO) for new synthetic routes. The investigation of the reactive processes in computational chemistry steps, essentially, by calculations of electronic energy, in which information is obtained on the energies and the relative structural changes of the species involved in the chemical reactions. In this work, computational methods were used to understand how mechanical processes occur: 1-morpholine-1-cyclohexene reacting with nitrosobenzene and 1-pyrrolidine-1-cyclohexene also reacting with nitrosobenzene. All optimized geometries of reaction were calculated using the DFT method, functional / base set M06-2X / 6-31+G(d,p). After this step, the single point was made of these optimized geometries, but we used the B2PLYPD3 functional and the base set 6-311G(2d,p), to obtain more accurate results. The results showed that the reaction process goes through three stages: transition states 1 (TS1), zwitterionic intermediates and transition states 2 (TS2). Analogously to the reactions of Diels-Alder, the reactions studied present endo and exo isomerism. It led to eight possible confomation for the TS1 of each reaction, as well as for the intermediates. In TS2, however, only 4 structure was obtained for reaction with 1-morpholinecyclohexene, whereas structures with exo isomeria would change to endo isomerism. However, with pyrrolidine, two conformations were obtained. Furthermore, for the reaction of 1-morpholinecyclohexene, a reaction mechanism was presented which corroborates with experimental studies. With 1-pyrrolidinecyclohexene, the method used was not effective to be in agreement with experimental results. Thus, this work provides a perspective for elucidation of the aldol N- / O-Nitroso reaction.

MEMBROS DA BANCA:
Presidente - 1859346 - MIGUEL ANGELO FONSECA DE SOUZA
Interno - 1959889 - DAVI SERRADELLA VIEIRA
Externo à Instituição - GUTTO RAFFYSON SILVA DE FREITAS - IFRN