Estudos sobre a resolução cinética dinâmica de álcoois e aminas utilizando diferentes líquidos iônicos dos tipos sais de amônio e de fosfônio
Data
2022-06-20
Autores
Silva, Gabriele Martins da 
Orientadores
Siqueira, Fernanda Amaral de
Tipo
Trabalho de conclusão de curso
Título da Revista
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Resumo
Aminas e álcoois opticamente ativos fazem parte de importantes classes de compostos orgânicos e podem ser obtidos através da Resolução Cinética Enzimática de uma mistura racêmica. Nessa metodologia é utilizada uma enzima, que é a responsável pela etapa de enantiosseletividade da reação, permitindo a obtenção de compostos enantiomericamente puros. A desvantagem dessa metodologia é que o rendimento máximo obtido é de 50%. Uma alternativa a essa limitação é a Resolução Cinética Dinâmica (RCD), na qual se faz o uso de um catalisador metálico, responsável por racemizar o enantiômero remanescente. Desta forma, é possível chegar a um rendimento teórico de 100%. Nesse projeto, foram usados três substratos diferentes: 1-tetralol, 1-feniletanol e 1-feniletilamina. Escolhemos Pd/BaSO4 como catalisador metálico e CaLB (Candida Antartida Lipase– fração B) como catalisador enzimático, ambos comerciais. As reações foram também realizadas na presença de 4 líquidos iônicos diferentes, dos tipos sais de amônio e de fosfônio. Após otimizações, considerou-se 24h como o melhor tempo reacional tanto para as aminas quanto para os álcoois. Além disso, a temperatura de 80ºC foi considerada a melhor para as aminas, enquanto 60ºC foi a melhor para os álcoois. De maneira geral, foi possível demonstrar os benefícios dos líquidos iônicos, visto que os resultados obtidos para conversão, rendimento e excesso enantiomérico foram melhores na presença desses aditivos.
Optically active amines and alcohols are part of an important classes of organic compounds and can be obtained by Enzymatic Kinetic Resolution of a racemic mixture. In this methodology is used an enzyme, that is responsible for the enantioselectivity of the reaction, allowing enantiomerically pure compounds. The disadvantage of this methodology is that the maximum yield obtained is 50%. An alternative to this limitation is Dynamic Kinetic Resolution (DKR), in which is included metallic catalyst, responsible for racemization of the remaining enantiomer. In this way, it is possible to reach a theoretical yield of 100%. In this project, three different substrates were used: 1-tetralol, 1-phenylethanol and 1-phenylethylamine. We choose Pd/BaSO4 for metallic and CaLB (Candida Antartida Lipase - fraction B) for enzymatic catalysis, both commercially available. The reactions were also performed in the presence of 4 different ionic liquids, ammonium and phosphonium salts. After optimizations, 24 hours was considered the best reaction time for both (amines and the alcohols). In addition, the best temperature for amines was 80ºC, while 60ºC was the best for alcohols. In general, it was possible to demonstrate the benefit of the ionic liquids, since the results obtained for conversion, yield and enantiomeric excess were better in the presence of these additives.
Optically active amines and alcohols are part of an important classes of organic compounds and can be obtained by Enzymatic Kinetic Resolution of a racemic mixture. In this methodology is used an enzyme, that is responsible for the enantioselectivity of the reaction, allowing enantiomerically pure compounds. The disadvantage of this methodology is that the maximum yield obtained is 50%. An alternative to this limitation is Dynamic Kinetic Resolution (DKR), in which is included metallic catalyst, responsible for racemization of the remaining enantiomer. In this way, it is possible to reach a theoretical yield of 100%. In this project, three different substrates were used: 1-tetralol, 1-phenylethanol and 1-phenylethylamine. We choose Pd/BaSO4 for metallic and CaLB (Candida Antartida Lipase - fraction B) for enzymatic catalysis, both commercially available. The reactions were also performed in the presence of 4 different ionic liquids, ammonium and phosphonium salts. After optimizations, 24 hours was considered the best reaction time for both (amines and the alcohols). In addition, the best temperature for amines was 80ºC, while 60ºC was the best for alcohols. In general, it was possible to demonstrate the benefit of the ionic liquids, since the results obtained for conversion, yield and enantiomeric excess were better in the presence of these additives.