Dimetilsulfóxidos como ligantes ancilares em complexos de rutênio: catalisadores duais para a combinação da ROMP de norborneno e ATRP de metacrilato de metila
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Data
2016-02-23
Autores
Borim, Patricia [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os complexos [RuCl2(S-dmso)3(O-dmso)] (complexo 1) e [RuCl2(PPh3)(S-dmso)2] (complexo 2) foram sintetizados e caracterizados por RMN, FTIR, voltametria cíclica e análise elementar. A atividade catalítica dos complexos 1 e 2 foi investigada na polimerização por abertura de anel via metátese (ROMP) de norborneno (NBE) e na polimerização radicalar por transferência de átomo (ATRP) de metacrilato de metila (MMA). As sínteses de polinorborneno (poliNBE) via ROMP com [RuCl2(PPh3)(S-dmso)2] como pré-catalisador foram avaliadas sob diferentes condições de reação ([EDA]/[Ru], [NBE]/[Ru], temperatura e tempo de reação). Os melhores rendimentos de poliNBE foram obtidos a 50 °C durante 120 minutos com razão molar [NBE]/[Ru] = 5000, na presença de 5 µL de EDA. A polimerização de MMA via ATRP foi conduzida independentemente usando os complexos 1 ou 2. Os testes catalíticos na ATRP de MMA foram avaliados em função das razões molares [EBiB]/[Ru] e [MMA]/[Ru] e do tempo de reação. Todos os experimentos via ATRP foram conduzidos à 85 °C. As polimerizações realizadas com 2 mostraram que as massas moleculares aumentaram linearmente com a conversão. As massas moleculares obtidas no estudo cinético com 1 também aumentaram com a conversão, mas foram maiores do que as massas moleculares teóricas. Este comportamento pode ser explicado pelo processo redox reversível de 2, como confirmado por voltametria cíclica. O complexo [RuCl2(PPh3)(S-dmso)2] (2) demonstrou menor atividade catalítica do que o complexo [RuCl2(S-dmso)3(O-dmso)] (1), o qual é consistente com o melhor controle na polimerização.
The [RuCl2(S-dmso)3(O-dmso)] (1) and [RuCl2(PPh3)(S-dmso)2] (2) complexes were synthesized and characterized by NMR, FTIR, cyclic voltammetry and elementary analysis. Their catalytic activity was investigated in the ring-opening metathesis polymerization (ROMP) of norbornene (NBE) and in the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). Syntheses of polynorbornene (polyNBE) via ROMP with 2 as precatalyst were evaluated under different reaction conditions ([EDA]/[Ru], [NBE]/[Ru], temperature and reaction time; EDA is ethyldiazoacetate). PolyNBE yields were dependent on the EDA volume, monomer concentration, temperature and reaction time. The best yields of polyNBE were obtained at 50 °C for 120 min with [NBE]/[Ru] = 5000 in presence of 5 µL of EDA. MMA polymerization via ATRP was conducted independently using the complexes 1 and 2 as catalysts as a function of time and initiator and monomer concentration. The kinetic data for polymerizations carried out with 2 show that molecular weights increase linearly with conversion. The molecular weights obtained in the kinetic study with 1 also increase with conversion but show a marked deviation above the theoretical molecular weights. This behavior was explained by the reversible redox process of 2 as confirmed by cyclic voltammetry. The complex [RuCl2(S-dmso)2(PPh3)] (2) promotes the polymerization with a rate of polymerization slower than that obtained using the complex [RuCl2(S-dmso)3(O-dmso)] (1); it is consistent with the better control in the polymerization.
The [RuCl2(S-dmso)3(O-dmso)] (1) and [RuCl2(PPh3)(S-dmso)2] (2) complexes were synthesized and characterized by NMR, FTIR, cyclic voltammetry and elementary analysis. Their catalytic activity was investigated in the ring-opening metathesis polymerization (ROMP) of norbornene (NBE) and in the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). Syntheses of polynorbornene (polyNBE) via ROMP with 2 as precatalyst were evaluated under different reaction conditions ([EDA]/[Ru], [NBE]/[Ru], temperature and reaction time; EDA is ethyldiazoacetate). PolyNBE yields were dependent on the EDA volume, monomer concentration, temperature and reaction time. The best yields of polyNBE were obtained at 50 °C for 120 min with [NBE]/[Ru] = 5000 in presence of 5 µL of EDA. MMA polymerization via ATRP was conducted independently using the complexes 1 and 2 as catalysts as a function of time and initiator and monomer concentration. The kinetic data for polymerizations carried out with 2 show that molecular weights increase linearly with conversion. The molecular weights obtained in the kinetic study with 1 also increase with conversion but show a marked deviation above the theoretical molecular weights. This behavior was explained by the reversible redox process of 2 as confirmed by cyclic voltammetry. The complex [RuCl2(S-dmso)2(PPh3)] (2) promotes the polymerization with a rate of polymerization slower than that obtained using the complex [RuCl2(S-dmso)3(O-dmso)] (1); it is consistent with the better control in the polymerization.
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Palavras-chave
Dimetilsulfóxido, ROMP, ATRP, Catalisadores, Rutênio, Dimethyl-sulfoxide, Catalysts, Ruthenium