Sistemas catalíticos heterogêneos para reações de acoplamento Stille-Migita

• Ano de defesa: 2019
• Autor(a) principal: Godoy, Pedro Henrique Machado
• Orientador(a): Alonso, Christian Gonçalves
• Banca de defesa: Alonso, Christian Gonçalves, Ostroski, Indianara Conceição, Chagas, Rafael Pavão das
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Goiás
• Programa de Pós-Graduação: Programa de Pós-graduação em Engenharia Química (IQ)
• Departamento: Instituto de Química - IQ (RG)
• País: Brasil
• Palavras-chave em Português: Reações de acoplamento orgânico; Reação de Stille; Catálise heterogênea; Impregnação por excesso de solvente
• Palavras-chave em Inglês: Organic coupling reactions; Stille reaction; Catalysis heterogeneous; Excess solvent impregnation
• Área do conhecimento CNPq: ENGENHARIAS::ENGENHARIA QUIMICA
• Link de acesso: http://repositorio.bc.ufg.br/tede/handle/tede/10047

Carbon-carbon coupling reactions are of fundamental importance in the synthesis of organic compounds. The Stille-Migita reaction is a cross-coupling reaction and occurs when an organotin compound and an organic halide hybridized to sp3 react under the presence of a metal-based catalyst, generally palladium. The reaction has the advantage of being compatible with virtually any functional group and for forming products with complex chains, such as pharmaceuticals and agrochemicals. However, Stille synthesis is usually performed by homogeneous catalysis, which enhances the need for costly purification processes necessary to remove metal debris from the reaction products. Thus, this work synthesized and verified the use of heterogeneous catalysts for Stille coupling reactions, using the efficient and economical method of wet impregnation in its preparation by producing monometallic catalysts with different oxides as support. The catalysts were characterized before and after calcination by thermogravimetry and differential thermal analysis (TG / DTA), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), textural analysis by adsorption/desorption isotherms of N2 and X-ray fluorescence (XRF). The reaction parameters were optimized: time, temperature, type of solvent and catalyst composition. The materials La2O3/Pd and TiO2/Pd showed no catalytic activity, whereas the catalysts Nb2O5/Pd and SiO2/Pd showed good conversions, above 80%. The recycling tests showed considerable loss of activity, which could be associated with filtration and leaching of the active phase between cycles. Nb2O5/Pd showed higher efficiency in the presence of non-toxic solvents (water/ethanol), unusual in Stille reactions. It is expected that this work will contribute to the development of heterogeneous catalysis, particularly in the coupling reactions, since economical methods of synthesis have produced catalytically active materials.