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

Author(s)

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

• Document type: Journal article
• Source: MOLECULAR CATALYSIS; v. 528, p. 11-pg., 2022-07-22.

Abstract

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)

• FAPESP's process: 18/01258-5 - Novel chemical catalytic and photocatalytic processes for the direct conversion of methane and CO2 to products
• Grantee: José Maria Correa Bueno
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 21/12342-0 - Production of bifunctional carbons for catalytic conversion of polyols and terpenes
• Grantee: Wagner Alves Carvalho
• Support Opportunities: Regular Research Grants