Complexos de rutênio coordenados a aminas cíclicas e bifosfinas como catalisadores duais em reações mecanisticamente incompatíveis (ROMP e ATRP)
Arquivos
Data
2019-02-08
Autores
Gois, Patrik Dione de Santana
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A investigação de sistemas catalíticos duais capazes de mediar as reações de polimerização por abertura de anel via metátese (ROMP) e de polimerização radicalar por transferência de átomo (ATRP) simultaneamente é de grande interesse e importância na obtenção de novos materiais com potencial aplicação. Neste estudo, complexos de rutênio(II) inéditos coordenados a diferentes aminas cíclicas (pirrolidina, piperidina e peridroazepina) foram sintetizados: [RuCl2(dppb)(pirrolidina)] (1), [RuCl2(dppb)(piperidina)] (2) e [RuCl2(dppb)(peridroazepina)] (3). Os complexos 1, 2 e 3 foram obtidos a partir da reação entre o complexo [RuCl2(dppb)(PPh3)] com a respectiva amina cíclica em acetona. Os complexos 1, 2 e 3 foram caracterizados por EPR, FTIR, UV-Vis, RMN de 31P e 1H e voltametria cíclica. Os complexos planejados foram avaliados como precursores catalíticos em reações de ROMP de norborneno (NBE). As sínteses de polinorborneno (poliNBE) via ROMP com os complexos 1, 2 e 3 como pré-catalisadores foram avaliadas sob condições de reação ([EDA]/[Ru] = 28 (5 µL), [NBE]/[Ru] = 5000, variando o tempo de 10 a 60 minutos a 25 e 50 ºC. A atividade catalítica dos complexos em ROMP de NBE demonstrou a seguinte ordem de reatividade: 3 > 2 > 1, a qual está relacionada ao maior sinergismo aminaRuolefina. A polimerização de MMA via ATRP foi conduzida usando os complexos 1, 2 e 3 na presença de etil-α-bromoisobutirato (EBiB) como iniciador. Os testes catalíticos foram avaliados em função do tempo de reação usando a razão molar [MMA]/[EBiB]/[Ru] = 1000/2/1. Todos os experimentos via ATRP foram conduzidos à 85 °C. As massas moleculares aumentaram linearmente com a conversão somente para o complexo 3, como esperado em uma polimerização controlada, no entanto, as massas moleculares experimentais foram maiores do que as massas moleculares teóricas.
The investigation of dual catalytic systems able to mediate simultaneously ringopening metathesis polymerization (ROMP) and atom-transfer radical polymerization (ATRP) reactions are of great interest and importance in obtaining new materials with potential for application. In the study, a series of three amineruthenium(II) complexes (amine = pyrrolidine, piperidine and perhydroazepine) was synthesized: [RuCl2(dppb)(pirrolidina)] (1), [RuCl2(dppb)(piperidina)] (2) and [RuCl2(dppb)(peridroazepina)] (3). Complexes 1, 2 and 3 were synthesized from the reaction between the [RuCl2(dppb)(PPh3)] complex and the respective amine in acetone. Complexes 1, 2 and 3 were characterized by EPR, FTIR, UV-Vis, 31P and 1H NMR, and cyclic voltammetry. The catalytic activity of complexes was evaluated in ROMP of norbornene (NBE). The synthesis of polynorbornene via ROMP using complexes 1, 2 and 3 as pre-catalysts was evaluated under reaction conditions of [EDA]/[Ru] = 28 (5 μL), [NBE]/[Ru] = 5000 at 25 and 50 °C as a function of time (10 to 60 min). The catalytic activity of the complexes for ROMP of NBE showed the following order of reactivity: 3 > 2 > 1, which is related to the greater -donation from the amine. The polymerization of MMA via ATRP was conducted using the complexes 1, 2 e 3 in the presence of ethyl 2-bromoisobutyrate (EBiB) as the initiator. All tests were made using the molar ratio [MMA]/[EBiB]/[Ru] = 1000/2/1 and conducted at 85 °C. For complex 3, molecular weights increased linearly with conversion, however, the experimental molecular weights were higher than the theoretical ones.
The investigation of dual catalytic systems able to mediate simultaneously ringopening metathesis polymerization (ROMP) and atom-transfer radical polymerization (ATRP) reactions are of great interest and importance in obtaining new materials with potential for application. In the study, a series of three amineruthenium(II) complexes (amine = pyrrolidine, piperidine and perhydroazepine) was synthesized: [RuCl2(dppb)(pirrolidina)] (1), [RuCl2(dppb)(piperidina)] (2) and [RuCl2(dppb)(peridroazepina)] (3). Complexes 1, 2 and 3 were synthesized from the reaction between the [RuCl2(dppb)(PPh3)] complex and the respective amine in acetone. Complexes 1, 2 and 3 were characterized by EPR, FTIR, UV-Vis, 31P and 1H NMR, and cyclic voltammetry. The catalytic activity of complexes was evaluated in ROMP of norbornene (NBE). The synthesis of polynorbornene via ROMP using complexes 1, 2 and 3 as pre-catalysts was evaluated under reaction conditions of [EDA]/[Ru] = 28 (5 μL), [NBE]/[Ru] = 5000 at 25 and 50 °C as a function of time (10 to 60 min). The catalytic activity of the complexes for ROMP of NBE showed the following order of reactivity: 3 > 2 > 1, which is related to the greater -donation from the amine. The polymerization of MMA via ATRP was conducted using the complexes 1, 2 e 3 in the presence of ethyl 2-bromoisobutyrate (EBiB) as the initiator. All tests were made using the molar ratio [MMA]/[EBiB]/[Ru] = 1000/2/1 and conducted at 85 °C. For complex 3, molecular weights increased linearly with conversion, however, the experimental molecular weights were higher than the theoretical ones.
Descrição
Palavras-chave
polimerização, catálise, norborneno, metacrilato de metila, caracterização, Polymerization, Catalysis, Norbornene, Methyl methacrylate, Characterization