Licenciatura em Química (UAST)
URI permanente desta comunidadehttps://arandu.ufrpe.br/handle/123456789/2945
Siglas das Coleções:
APP - Artigo Publicado em Periódico
TAE - Trabalho Apresentado em Evento
TCC - Trabalho de Conclusão de Curso
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Resultados da Pesquisa
Item Estudo computacional das reações SN2 e E2: efeito do impedimento estérico do substrato e nucleófilo(2017) Carvalho Júnior, Jailson Alves de; Souza, Túlio Ricardo Couto de Lima; http://lattes.cnpq.br/8553398552801408; http://lattes.cnpq.br/5851976775229056Reactions SN2 and E2 are typical reactions of organic chemistry and there are a multitude of reactions in this segment, these are presented as fundamental in the synthesis, both in industry and in nature. And based on these utilities, we will show here the influence of some variables such as substrate, nucleophile and solvent will favor one of the two reactions, although they occur simultaneously, but with predominance of one over the other in all cases. Thus, in the present work two theoretical computational methods were developed with the aid of the GAUSSIAN 5.0.8 programfor the kinetic and thermodynamic study of these reactions, as well as the ideal conditions for their occurrence. In the first part of the study, there was a relative comparison between the two reactions at the semiempirical level AM1 and PM6, in the two methods the E2 reactions did not have expected behavior for the primary alkyl halides, whereas SN2 in the AM1 method also caused anomalous results, but In the PM6 method was presented as expected. Thus the study of the E2 reactions was terminated. The second part of the study was focused only on the SN2 reactions, in which several experiments were performed with different electrophiles and nucleophiles simulating an implicit methanol solvate medium (IEFPCM) at semiempirical PM6 level. The results were optimistic and corresponded to the expectations of the study, where factors such as steric effects on the electrophile, nucleophile and reactive medium had positive influences on the final result, following a tendency of reactivity imposed by experimental analyzes.Item Alilação do tipo Barbier de Aldeídos aromáticos promovida por Zn e catalisada por L-Prolina em meio aquoso(2019) Souza, Fabrícia Aparecida Marques de; Silva, Renato Augusto da; http://lattes.cnpq.br/5111987334920733; http://lattes.cnpq.br/0102375050840904Given the various strategies to form C-C bonding, involving organometallic intermediates, the Barbier reaction has proved to be an important methodology that can be performed efficiently in aqueous media with several advantages.The use of organocatalysts has also been very advantageous in various chemical reactions to a synthesis of safe and environmentally correct products.In this work, synthetic methodologies were studied to obtainhomoallyl alcoholsby means of alilation of the Barbier type. In order to follow the principles of green chemistry, the method relies on allylation reactions from aromatic aldehydes, allyl bromide, zinc and L-proline as catalyst, using water as the solvent. Aromatic aldehydes with allyl bromide, zinc and a 20% L-proline as catalyst were tested, being 4-F-benzaldehyde, 4-OMe-benzaldehyde and 2-naphthaldehyde using water as the solvent. Secund, the increase in the amount of L-proline to 80% was added and 3 aromatic aldehydes were tested, being 4-F-benzaldehyde, 2-OH-benzaldehyde and 2-OMe-benzaldehyde with allyl bromide, zinc and water. All data were previously monitored by CG-FID and CCD and the homoallyl alcoholswere characterized from the respective signals by GC-MS, throughcomputerized comparison of the library masses of the apparatus itself and the specific fragmentation pattern.In the first 3, with 20% L-proline, excellent conversions were detected, but 4-F-benzaldehyde was fully converted to 1-(4-fluorophenyl) but-3-en-1-ol with only 1h of magnetic stirring , 4-OMe-benzaldehyde converted to 1-(4-methoxyphenyl) but-3-en-1-ol with 4h and 2-naphthaldehyde converted to 1-(2-naphthyl) but-3-en-1-ol with 1h, in all cases, without formation of by-products. Subsequently, in the last 3 assays, with 80% proline L, the reaction time of 4-F-benzaldehyde was reduced to 30 minutes with complete conversion of the 1-(4-fluorophenyl) but-3-en-1-ol alcohol; 2-OH-benzaldehyde and 2-OMe-benzaldehyde were converted respectively into 1-(2-hydroxyphenyl) but-3-en-1-ol and 1-(2-methoxyphenyl) but-3-en-1, however, traces of the starting materials were still detected. The 1-(4-fluorophenyl) but-3-en-1-ol and 1-(2-naphthyl) but-3-en-1-ol alcohols were also characterized by 1 H and ¹³C NMR.