Search

To promote scientific progress and optimize the utilization of natural plant resources that rich in selenium, the study selected selenium-rich Hibiscus manihot L. as the research object, using the HG-AFS to detect the selenium content in different plant organ samples, ultrasound assisted ethanol extraction of selenium containing organic active components from sunflower flowers, and obtaining the optimal extraction process by response surface methodology. At the same time, conducting antioxidant activity research on selenium containing extracts. The results showed that the total Se concentrations in different organs of Hibiscus manihot L., from highest to lowest were found in the leaves, fruits, flowers, roots, and stems, with concentrations of 21.99, 14.29, 12.93, 10.90, and 10.23 mg/kg, respectively. The RSM optimization results indicated that the ideal conditions for the extraction parameters were as follows: Extraction temperature of 40 °C, solid-liquid ratio of 1:60, extraction time of 40 minutes, ultrasonic power of 350 W, ethanol concentration of 50% (V/V), under one-time extraction. For the optimal conditions, the selenium extraction rate was 36.65%±0.65%. The DPPH antioxidant activity analysis showed a half-inhibitory concentration (IC50) value of 0.048 mg/mL (with a Se concentration of 0.79 μg/mL), the hydroxyl radical scavenging analysis showed that the maximum clearance rate was 97% when the extracts concentration was 8 mg/mL, and the IC50 was 0.56 mg/mL. The reducing power analysis showed that the reducing power of the extracts increases with the increase of the concentration, indicating that the extracts possess a good antioxidant capacity. The present study would provide empirical evidence to support the efficient use of selenium-rich Hibiscus manihot L. and the extraction of selenium-rich agricultural by-products. [ABSTRACT FROM AUTHOR]

The one-pot catalytic conversion of cellulose into ethylene glycol (EG) is an attractive way of biomass utilization. However, low-cost, efficient, and stable catalysts are the premise and research challenges of industrial application. Herein, the magnetic recyclable W–Ni@C catalyst was synthesized by in-situ pyrolysis of Ni-MOFs impregnated with ammonium metatungstate. Compared with the Ni-W bimetallic catalysts prepared by the impregnation method and the sol–gel method, the W–Ni@C catalyst for cellulose hydrogenolysis reaction can achieve a higher ethylene glycol yield (67.1% vs 43.3% and 42.6%) and 100% of cellulose conversion rate. The uniformly dispersed Ni nanoparticles and abundant defective WOx were formed in a reductive atmosphere generated in pyrolysis of Ni-MOFs, which was indispensable for the hydrogenolysis of cellulose into EG. Besides, the hierarchical porous carbon derived from organic ligands in Ni-MOFs reduces the mass transfer resistance while confining Ni nanoparticles and WOx to prevent their leaching, effectively enhancing the stability of the W–Ni@C catalyst. Therefore, the remarkable catalytic performance, the simple and effective recovery method as well as satisfying stability would make W–Ni@C become a promising catalyst for the conversion of cellulose to EG. [ABSTRACT FROM AUTHOR]

Titanocene perfluorooctanesulfonate is air-stable complex. In the presence of 10 mol% of the complex, reductive cleavage of an S-S bond by zinc in commercial tetrahydrofuran at room temperature led to nucleophilic sulfur anion species, which reacted with acid anhydrides to afford thioesters in good to excellent yields. [ABSTRACT FROM AUTHOR]

In the presence of a catalytic amount of cesium hydroxide under a nitrogen atmosphere, terminal alkynes reacted with diaryl disulfides at room temperature in dimethylformamide to give almost exclusively (Z)-1,2-diarylthio-1-alkene in good yields, but under an air atmosphere, the reaction gave a mixture of alkynyl sulfide and (Z)-1,2-diarylthio-1-alkene. [ABSTRACT FROM AUTHOR]

Stable complexes: An extremely air-stable mu(2)-hydroxy-bridged binuclear hafonocene perfluorooctanesulfoante complex shows high catalytic efficiency in Lewis acid-catalyzed reactions, such as esterification, Friedel-Crafts acylation, the Mukaiyama aldol reation, and the allylation of aldehyde (see scheme).An extremely air-stable mu(2)-hydroxy-bridged binuclear hafonocene perfluorooctanesulfoante complex was successfully synthesized. This complex showed high catalytic efficiency in the esterification of alcohols, phenol, thiol, and amines, in the Friedel-Crafts acylation of alylaryl ethers, in the Mukaiyama aldol reaction, and in the allylation of aldehydes and could be reused.