Triphasic Hydroxysilylation of Alkenes by Mechanically Piezoelectric Catalysis.

The 1,2-hydroxysilylation of alkenes is crucial for synthesizing organosilicon compounds which are key intermediates in material science, pharmaceuticals, and organic synthesis. The development of strategies employing hydrogen atom transfer pathways is currently hindered by the existence of various competing reactions. Herein, we reported a novel mechanochemical strategy for the triphasic 1,2-hydroxysilylation of alkenes through a single-electron-transfer pathway.

Mechanochemical Vicinal Dibromination of Unactivated Alkenes and Alkynes Using Piezoelectric Material as a Redox Catalyst.

Mechanoredox chemistry is a rapidly evolving field at the intersection of mechanical forces and chemical reactions. Herein, we have reported a vicinal dibromination of unsaturated hydrocarbons using piezoelectric material (LiTiO) as a redox catalyst. Furthermore, the reaction can be efficiently scaled up to 10 mmol and performed under an air atmosphere at room temperature without solvents or external reductants, and LiTiO can be reused multiple times without a structural change.

Novel dental composites reinforced with zirconia-silica ceramic nanofibers.

Objective: To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers.

Methods: Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.

Fabrication and characterization of dense zirconia and zirconia-silica ceramic nanofibers.

The objective of this study was to prepare dense zirconia-yttria (ZY), zirconia-silica (ZS) and zirconia-yttria-silica (ZYS) nanofibers as reinforcing elements for dental composites. Zirconium (IV) propoxide, yttrium nitrate hexahydrate, and tetraethyl orthosilicate (TEOS) were used as precursors for the preparation of zirconia, yttria, and silica sols. A small amount (1-1.

Synthesis of TiO2 photocatalysts in supercritical CO2 via a non-hydrolytic route.

Nanoscaled TiO2 powders with narrow size dispersion were prepared in supercritical carbon dioxide via non-hydrolytic acylation/deacylation of titanium alkoxide precursors with or without tris-fluorination. The microstructures of these powders were characterized by spectroscopic (FTIR, TGA, and XRD), microscopic (SEM or TEM), and surface area (BET) measurements. Photocatalytic oxidation of 1-octanol on these calcined TiO2 powders and on commercial T805 TiO2 suspended in aerated supercritical carbon dioxide revealed relative reactivity controlled by the powder microstructures.