Transformações de substratos biorrenováveis catalisadas por heteropoliácidos

• Ano de defesa: 2020
• Autor(a) principal: Rafaela Ferreira Cotta Maciel
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; Brasil; ICX - DEPARTAMENTO DE QUÍMICA; Programa de Pós-Graduação em Química; UFMG
• Palavras-chave em Português: Solventes verdes; Heteropoliácidos; Monoterpenos; Acoplamento; Isomerização; Terpenes; Terpenoids; Química inorgânica; Química ambiental; Solventes; Compostos heterocíclicos; Catalisadores; Substratos; Biomassa; Limoneno; Terpenios
• Link de acesso: http://hdl.handle.net/1843/35886

In this work, several catalytic processes for the valorization of a series of natural monoterpenic compounds were developed, including limonene, a low cost and abundant substrate widely available in Brazil. All processes are in line with green chemistry concepts, with the use of renewable starting materials, green solvents, mild reaction conditions and in the presence of heterogeneous, non-toxic and non-corrosive catalysts. Coupling reactions between monoterpene compounds (limonene, α-terpineol, α-pinene, β-pinene, nerol or linalool) and aldehydes or epoxides (cuminaldehyde, trans-cinnamaldehyde, benzaldehyde, crotonaldehyde, phenylacetaldehyde or styrene oxide) were performed to obtain different oxygen-containing bicyclic and tetracyclic products in high yields. In these reactions, Cs2.5H0.5PW12O40 (CsPW) and silica-supported H3PW12O40 (HPW/SiO2) were used as acidic heterogeneous catalysts in green solvents, i.e., diethylcarbonate (DEC), dimethylcarbonate (DMC), anisole and biomass derived 2-methyltetrahydrofuran (MeTHF). The isomerization of limonene oxide using (HPW/SiO2) as heterogeneous catalyst was also studied to give dihydrocarvone and carvenone with 90% and 93% yields, respectively. The solvents that presented the best results were the ecologically friendly DEC and DMC. Finally, the stereoselective isomerization of cis-limonene oxide to give trans-dihydrocarvone in DMC solutions was also developed.