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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Nanomateriais organofuncionalizados e suas aplicações em catálise: associando as vantagens da catálise homogênea com as da heterogênea / Nanomaterials organofunctionalized and their applications in catalysis: the advantages of a member with the homogeneous catalysis heterogeneous

Inforzato, Tatiane 14 June 2013 (has links)
Made available in DSpace on 2016-06-02T20:34:51Z (GMT). No. of bitstreams: 1 5875.pdf: 3093779 bytes, checksum: 5229ef01b8b2206f72e4f4a81acd582c (MD5) Previous issue date: 2013-06-14 / Universidade Federal de Sao Carlos / We have immobilized proline, like prolinamide, by using flash chromatography with commercial grade silica and magnetite nanoparticles that were synthesized in our lab. The degree of functionalization has been determined by the nitrogen content from the data collected from elemental analysis of the particles. The organofunctionalization of the silica surface and the structure have been confirmed by 13C CP-TOS NMR and 29Si-NMR CPMAS solid state analysis. The confirmation of the catalyst-supported structure on functionalized magnetite can be correlated to the data obtained from the silica, since methodology was the same. The materials Pro-SiO2 and Fe3O4 @ SiO2-Pro were used in catalysis for the Michael reaction. The catalysts have been tested in several conditions: solvents, additive, reaction time and determined the minimum amount of catalyst needed to optimize reaction conditions. It was observed that the catalysis is best conducted without a solvent or in saturated NaCl solution and in the presence of additive, such as benzoic acid or acetic acid. The recyclability for both materials was satisfactory and no significant losses were observed after five cycles. The best results were obtained for propanone and cyclohexanone as a Michael donor and nitrostyrene as a Michael receptor with excellent yields and diastereoselectivity (in the case of cyclohexanone). Enantiomeric excess obtained for these reactions were too low to be observed proving the structural efficiency of the catalytic process. / Neste trabalho foi imobilizada a prolina, na forma de prolinamida, na sílica flash comercial e em nanopartículas de magnetita. Os materiais foram sintetizados e o grau de funcionalização foi adquirido através do teor de nitrogênio obtido da análise elementar. As estruturas foram confirmadas pela análise de 13C- RMN-CP-TOSS e 29Si-RMN-CPMAS no estado sólido para a sílica organofuncionalizada. A confirmação da estrutura do catalisador suportado na magnetita funcionalizada pode ser correlacionada com os dados obtidos da sílica, uma vez que a metodologia utilizada foi a mesma. Os materiais SiO2-Pro e Fe3O4@SiO2-Pro foram aplicados na catálise da reação de Michael. Os catalisadores foram testados em diversos solventes, aditivos, tempo de reação e quantidade de catalisador mínima até serem encontradas as condições ótimas de reação. A reação resulta em maior rendimento e diastereosseletividade quando conduzidas sem solvente ou em solução saturada de NaCl, na presença dos aditivos ácido benzóico ou acético. Suas reciclabilidades foram satisfatórias, não tendo perdas significativas após cinco ciclos. Os melhores resultados foram obtidos para a cicloexanona e propanona como doadores de Michael e nitroestireno como aceptor de Michael. Mesmo obtendo excelentes rendimentos e diastereosseletividades, os excessos enantioméricos obtidos foram de baixo valor.

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