Syntheses and catalytic activities of new metallodendritic catalysts

Author(s)

Vieira, Eduardo Guimaraes ; Silva, Rafael Oliveira ; Dal-Bo, Alexandre Goncalves ; Allievi Frizon, Tiago Elias ; Dias Filho, Newton Luiz

• Document type: Journal article
• Source: NEW JOURNAL OF CHEMISTRY; v. 40, n. 11, p. 9403-9414, 2016.
• Web of Science Citations: 5

Abstract

This investigation presents the syntheses of new metallodendritic catalysts from a silsesquioxane core (Silsesq-PrNH3+Cl-) via a new route. For optimization of the syntheses of the catalysts, reaction times, thermodynamic effects, and the amounts of {[}Mo(eta(3)-C3H5)Br(CO)(2)(NCCH3)(2)] (1) and {[}Mo(CO)(3)Br-2(NCCH3)(2)] (2) complexes fixed on the second-generation dendrimer (PDG2.0) were studied. After the optimization studies and with the objective of application in catalysis, the catalysts were prepared by reaction of PDG2.0 with the organometallic complexes and characterized by elemental analysis (CNH), FTIR, C-13 and Si-29 NMR, XRD, TGA, SEM, EDS and BET. The metallodendritic catalysts were tested in the epoxidation of olefins and shown to be a vigorous catalyst with conversion rates between 76 and 97% for PDG2.0-{[}(Mo(eta(3)-C3H5)(CO)(2)Br)(8)] and 30-80% for PDG2.0-{[}(Mo(CO)(3)Br-2)(5)], and a high selectivity in the formation of epoxides using tertbutyl hydroperoxide (TBHP) as an oxidant. The catalysts remain highly active after being used for at least 5 cycles. To the best of our knowledge, this study is the first to have reported the preparation of these new dendritic catalysts, as well as the catalytic comparison with their previous generations in the epoxidation of 1-octene, cyclooctene, (S)-limonene, cis-3-hexen-1-ol, trans-3-hexen1-ol and styrene. (AU)

• FAPESP's process: 14/05566-5 - Study of the reactions of immobilization of tungsten and molybdenum organometallic complexes on the polyhedral oligomeric silsesquioxanes for application in catalysis
• Grantee: Eduardo Guimarães Vieira
• Support type: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/24602-0 - Synthesis and characterization of polyhedral oligomeric silsesquioxanes and their applications in process of adsorption and catalysis
• Grantee: Newton Luiz Dias Filho
• Support type: Regular Research Grants