Hydrophobic TaOx Species Overlayer Tuning Light-Driven Methane Chlorination with Inorganic Chlorine.

Halogenated methane serves as a universal platform molecule for building high-value chemicals. Utilizing sodium chloride solution for photocatalytic methane chlorination presents an environmentally friendly method for methane conversion. However, competing reactions in gas-solid-liquid systems leads to low efficiency and selectivity in photocatalytic methane chlorination. Here, an in situ method is employed to fabricate a hydrophobic layer of TaOx species on the surface of NaTaO3. Through in-situ XPS and XANES spectra analysis, it is determined that TaOx is a coordination unsaturated species. The TaOx species transforms the surface properties from the inherent hydrophilicity of NaTaO3 to the hydrophobicity of TaOx/NaTaO3, which enhances the accessibility of CH4 for adsorption and activation, and thus promotes the methane chlorination reaction within the gas-liquid-solid three-phase system. The optimized TaOx/NaTaO3 photocatalyst has a good durability for multiple cycles of methane chlorination reactions, yielding CH3Cl at a rate of 233 µmol g-1 h-1 with a selectivity of 83%. In contrast, pure NaTaO3 exhibits almost no activity toward CH3Cl formation, instead catalyzing the over-oxidation of CH4 into CO2. Notably, the activity of the optimized TaOx/NaTaO3 photocatalyst surpasses that of reported noble metal photocatalysts. This research offers an effective strategy for enhancing the selectivity of photocatalytic methane chlorination using inorganic chlorine ions.

Palladium-Catalyzed Cascade Carbonylative Synthesis of Perfluoroalkyl and Carbonyl-Containing 3,4-Dihydroquinolin-2(1H)-one Derivatives.

A palladium-catalyzed cascade radical cyclization and carbonylation of 1,7-enynes with perfluoroalkyl iodides and alcohols has been described. This procedure provides a facile and efficient approach for the construction of 3,4-dihydroquinolin-2(1H)-one skeletons by using benzene-1,3,5-triyl triformate (TFBen) as the CO source. This method enables the incorporation of both perfluoroalkyl and carbonyl units into the 3,4-dihydroquinolin-2(1H)-one skeletons, producing a variety of 3,4-dihydroquinolin-2(1H)-one derivatives in moderate to high yields and with excellent E/Z selectivity.