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In light of the burgeoning biological applications associated with xanthones, the development of highly efficient synthetic methodologies for their production has emerged as a pivotal objective of chemical research. Amidst the array of available protocols, the oxidative carbonylation of diaryl ethers with carbon monoxide (CO) stands out as a notably uncomplicated route, often necessitating stoichiometric oxidants. Herein, we present a feasible approach employing unsymmetrical-waveform alternating current (AC) electrolysis to facilitate Pd-catalysed oxidative C–H/C–H carbonylation. Leveraging a straightforward catalytic system, we demonstrate the conversion of diverse diaryl ethers into xanthones with moderate to commendable yields. Our mechanistic investigations illuminate the indispensable role played by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in the electrochemical system, particularly its ability to recycle heterogeneous palladium species within the solution. [ABSTRACT FROM AUTHOR]

A highly efficient catalytic system was developed for the reaction between CO2 and propargylic alcohols for alkylidene cyclic carbonates. Ionic liquids (ILs) with different anions and cations were designed as cocatalysts, in order to find out the effect of the cation and the anion on this reaction. The results indicated that the effect of the cation was significant, especially the hydroxyl group on the cation played an important role due to the presence of a hydrogen bond. It was also found that the basicity of the anion was important for its catalytic activity, where the anion with moderate basicity gave the best activity. Moreover, this hydroxyl and azolate dual functionalized catalytic system showed excellent reusability and generality. It is worth mentioning that at a low concentration of CO2, this dual functionalized catalytic system showed excellent catalytic activity even in a gram-scale reaction, indicating its potential in carbon capture and utilization processes. [ABSTRACT FROM AUTHOR]

Catalytic functionalized aniline formation from nitroarenes is a core technology in the synthesis of pharmaceuticals, agrochemicals, and fine chemicals. However, control of chemoselectivity still poses particular challenges with aromatic nitro substrates bearing one or more reducible groups. Here, we report the low-cost synthesis of a porous carbon supported CoS2 catalyst (CoS2/PC) and successfully apply the catalyst in the chemoselective hydrogenation of nitroarenes. For hydrogenation of 3-nitrostyrene, the catalyst furnishes a superior selectivity of 99% towards 3-aminostyrene at a conversion of ＞99%. Density functional theory calculations together with X-ray absorption fine structure spectroscopy reveal that terdentate and tetrahedral coordinated Co atoms in CoS2 (labeled as Co3 and Co4) are possible active sites. The face to face located Co3 and Co4 sites make the reaction rather local, and Co3 and Co4 sites are occupied by substrates and H2, respectively, which is beneficial to the superior activity and selectivity. The Co3–Co4“synergic active site pair” in CoS2 makes the investigation of the synergic effects at the molecular level a reality on heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Integrated sorption systems consisting of 1 : 1 mixtures of an alcohol-functionalized ionic liquid and a superbase were found to be effective for CO2capture under atmospheric pressure, eliminating the use of volatile n-alkanols or water. Conversely, by using the current approach, there is no longer a requirement for maintaining scrupulously dry conditions. The effect of ionic liquid structure, choice of superbase, their relative ratios, the sorption temperature, and the reaction time on the absorption and release of CO2were investigated. Our results demonstrate that (i) this integrated ionic liquid–superbase system is capable of rapid and reversible capture of nearly one mole of CO2per mole of superbase, (ii) the captured CO2can be readily released by either mild heating or bubbling with an insert gas (N2, Ar), and (iii) this novel CO2chemisorption platform can be recycled with minimal loss of activity. This efficient and fully reversible catch-and-release process using non-volatile, task-specific ionic liquids provides an excellent alternative to current CO2capture technologies, which are based largely around volatile alkanols or alkylamines. Furthermore, our integrated ionic liquid–superbase system can be used as a novel medium for supported liquid membranes, for which they demonstrate both good selectivity and permeability in model CO2/N2gas separations. [ABSTRACT FROM AUTHOR]