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Metal-ligand cooperation in the catalytic oxidation of (R)-carvone by Ga (NO3)(3)/H2O21

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Autor(es):
Correia, Gilvan A. ; de Araujo, Marcos L. ; Carvalho, Wagner A. ; Sairre, Mirela ; Cerchiaro, Giselle ; Shul'pina, Lidia S. ; Kozlov, Yuriy N. ; ShulPin, Georgiy B. ; Kirillov, Alexander M. ; Mandelli, Dalmo
Número total de Autores: 10
Tipo de documento: Artigo Científico
Fonte: MOLECULAR CATALYSIS; v. 528, p. 11-pg., 2022-07-22.
Resumo

In this work, the catalytic epoxidation of (R)-carvone by the Ga (NO3)(3)/H2O2 system was studied alongside the metal-ligand cooperation by exploring 17 different ligands. It was observed that the acidic ligands such as acetic acid mostly favor the epoxidation of the endocyclic double bond of (R)-carvone (22% yield, 1 h), while nitrogen heterocycles direct the epoxidation to the exocyclic double bond, especially the ones that are unsubstituted or have electron-donating groups, such as pyrazine (28% yield, 5 h), 4-dimethylaminopyridine (28% yield, 8 h), and 1-methyimidazole (43% yield, 8 h). Pyrazinecaboxylic acid favored the epoxidation of the exocyclic double bond (25%, 3 h). EPR analysis of both Ga(NO3)3/H2O2 and Ga(NO3)3/PCA/H2O2 systems indicates the presence of hydroxyl radicals in the reaction medium, although these do not determine the epoxidation rate that is likely regulated by the interaction of Ga-peroxo complexes with (R)-carvone. This study contributes to widening the application of the cooperating ligand concept in molecular catalysis toward further development of more se-lective and efficient epoxidation reactions catalyzed by non-transition metal centers. (AU)

Processo FAPESP: 18/01258-5 - Novos processos catalíticos e fotocatalíticos para a conversão direta de metano e CO2 em produtos
Beneficiário:José Maria Correa Bueno
Modalidade de apoio: Auxílio à Pesquisa - Temático
Processo FAPESP: 21/12342-0 - Produção de carvões bifuncionais para a conversão catalítica de polióis e terpenos
Beneficiário:Wagner Alves Carvalho
Modalidade de apoio: Auxílio à Pesquisa - Regular