The Al-Containing Silicates Modified with Organic Ligands and SnO2 Nanoparticles for Catalytic Baeyer-Villiger Oxidation and Aerobic Carboxylation of Carbonyl Compounds

Abstract

The Baeyer-Villiger Oxidation (BVO) of ketones and aldehydes produce lactones and formates, while aerobic carboxylation of aldehydes manufactures carboxylic acids, both having high added value. This work prepared a series of Al-containing silicates modified with organic ligands and SnO2 nanoparticles, which were then employed as catalyst in BVO and carboxylation. Characterizations revealed the morphology of the synthesized catalyst was changed from micron-sized thin sheets to smaller blocks, and then to uniform nanoparticles (size of 50 nm) having the doped SnO2 nanoparticles with a size of 29 nm. All catalysts showed high BET surface areas featuring silt-like mesopores. In determining the priority of BVO and carboxylation, an influence evaluation of the parameters showed the order to be substrate > oxidant > solvent > catalyst. Cyclic aliphatic ketones were suitable for BVO, but linear aliphatic and aromatic aldehydes for carboxylation. Coordination of (S)-binaphthol or doping of Sn into catalyst showed little influence on BVO under m-CPBA, but the Sn-doped catalyst largely increased BVO under (NH4)2S2O8 and H2O2. Calculations revealed that the catalyst containing both Al and Sn could give BVO intermediates lower energies than the Sn-beta zeolite model. The present system exhibited merits including wider substrate scope, innocuous catalytic metal, greener oxidant, as well as lower catalyst cost.

Periodate-Mediated Aerobic Oxidation of Sulfides over a Bifunctional Porphyrin-polyoxometalate Catalyst: Photosensitized Singlet Oxygen Oxidation of Iodate to Periodate

“…Most terminal oxidants used in biomimetic oxidation of organic compounds are consumed in stoichiometrically equivalent amounts. − ,− Regeneration of the reduced terminal oxidant by molecular oxygen is a green chemistry strategy for the replacement of chemical terminal oxidants with air as the most abundant, sustainable, and greenest oxidant. Photosensitized regeneration of the reagents consumed in chemical and biological transformations is an efficient approach to achieve this goal.…”

“…Over the past decades, different reagents such as molecular oxygen, , hydrogen peroxide, , alkyl hydroperoxides, , peracids, , hypervalent iodine compounds, , oxone, , hypochlorite, , and amine oxides , have been used as the terminal oxidants for metal-catalyzed oxidation of organic compounds. Transfer of oxygen from metal-coordinated ligands such as nitro group to an organic substrate, followed by the metal-catalyzed regeneration of the oxidant by molecular oxygen, has been reported as a new approach for the activation of electrophilic oxygens by Tovrog et al in 1979.…”

Mechanochemical Synthesis of PdO2 Nanoparticles Immobilized over Silica Gel for Catalytic Suzuki–Miyaura Cross-Coupling Reactions Leading to the C-3 Modification of 1H-Indazole with Phenylboronic Acids

“…In general, the binding energies of Si 2p photoelectrons can be found at 103.2-104.1 eV for C0-C3 (Figure S1a-d, Section S1, Supplementary Materials), which could be attributed to Si 4+ of the SiO2 phase [33]. Accordingly, C0-C3 all showed a broad XRD band in the range of 2θ = 15°-35°, centered at 23° (Figure 4a), corresponding to the typical diffraction of the silicate backbone coming from C0 (Scheme 1) [34].…”