Avaliação de rotas sustentáveis para a obtenção de ácido acetilsalicílico: contribuições para o ensino de Química Verde

Abstract

Green Chemistry consists of the design of safer and more sustainable chemical processes, being based on twelve principles that are applied in different contexts, among which the educational context stands out as one of the main ones. However, approaches that discuss the sustainability of Chemistry at different educational levels are still limited by the lack of teaching materials related to the topic. In this sense, this study aimed to evaluate alternative and sustainable routes for obtaining acetylsalicylic acid, comparing the effectiveness of less harmful substances in the synthesis of the drug and, based on the results obtained, to develop an experimental manual, with the aim of providing practical support for the inclusion of Green Chemistry in Chemistry teaching. To this end, in addition to the conventional synthesis, four adapted routes were analyzed. In three of them, the substitution of the sulfuric acid catalyst with phosphoric acid, citric acid, and sodium acetate was investigated, associated with a reduction in the amount of acetic anhydride, while in the last route the substitution of the anhydride with acetic acid was tested. Based on the results, it was possible to conclude that the route under phosphoric acid catalysis was the most viable for acetylation, a finding confirmed through identification tests with ferric chloride and melting point determination. Furthermore, this alternative showed superior performance in green aspects compared to the conventional method, as evaluated by the holistic Green Matrix metric. Thus, the developed educational product proved to be applicable both to the third year of high school and to undergraduate experimental courses, contributing as an alternative teaching material that addresses Green Chemistry in an experimental, contextualized, and safe way.