Bowei Wang

Reductive cyclization of 2-nitro-2′-hydroxy-5′-methylazobenzene to benzotriazole over K-doped Pd/γ-Al2O3

A series of Pd/γ-Al2O3 catalysts modified by potassium salts were prepared and evaluated in the reductive cyclization of 2-nitro-2′-hydroxy-5′-methylazobenzene without additional base. These solid base-hydrogenation bifunctional catalysts were characterized and the results demonstrated that potassium salts could have an important impact on the properties and catalytic performance of Pd/γ-Al2O3.

3D nitrogen-doped graphene gels as robust and sustainable adsorbents for dyes

Herein, a series of 3D nitrogen-doped graphene gels (NG) were synthesized for the removal of dyes from wastewater. Their structures were characterized by XRD, SEM, TEM, elemental analysis, BET analysis, and XPS. It was found that the distribution of functional groups on the NG surface could be significantly affected using different nitrogen sources, which could further influence their adsorption behaviors. Among them, the hybrid prepared from hexamethylenediamine as the nitrogen source shows best adsorbability for acidic dyes, whereas the hybrid obtained from ethylenediamine displays largest adsorption capacity for basic dyes. Adsorption isotherms and kinetics were also investigated. The results indicate that the best interpretation is provided by the Langmuir isotherm equation, and the adsorption dynamic behavior is fit for the pseudo-first-order model. In addition, intra-particle diffusion kinetics manifest rate-controlling steps including external diffusion and intra-particle diffusion. Moreover, all adsorbents exhibit excellent reusability. Therefore, NG adsorbents show potential applicative value in the treatment of dye wastewater.

Correction: 3D nitrogen-doped graphene gels as robust and sustainable adsorbents for dyes

Correction for ‘3D nitrogen-doped graphene gels as robust and sustainable adsorbents for dyes’ by Jiyu Geng et al., New J. Chem., 2017, 41, 15447–15457.

Co Entrapped in N, S co-doped Porous Carbon: Novel Catalyst for Transfer Hydrogenation with Formic Acid

Catalysts with Co nanoparticles (NPs) entrapped in N,S-codoped carbon shells were successfully fabricated by pyrolysis of porous organic polymers (POPs) with cobalt salts. The encapsulated structure consisting of Co NPs and N,S-codoped carbon layers was verified by TEM, XRD, and X-ray photoelectron spectroscopy. The catalysts displayed excellent activity and stability for the catalytic transfer hydrogenation (CTH) of nitrobenzene with formic acid under base-free conditions. Furthermore, the resultant catalysts allowed for highly efficient and selective transfer hydrogenation of various functionalized nitroarenes to the corresponding anilines. Through control experiments, the covered Co NPs were identified as active sites for CTH. The incorporation of S into the N-doped carbon lattice promoted the electron transfer from metallic cobalt NPs to their shells, which played a significant role in the acceleration of CTH. Moreover, the Co-NSPC-850 catalyst pyrolyzed at 850 °C showed excellent stability in the recycling experiments.

Wang resin-supported enantioselective catalysts for the asymmetric Michael additions of acetone to β-nitroolefins

Two Wang resin-supported (1R,2R)-(+)-1,2-DPEN(DPEN=diphenylthylenediamine) catalysts were synthesized from cyanuric chloride and trimesoyl chloride, respectively. These two catalysts were characterized by FTIR, TGA and elemental analysis. The results demonstrated that (1R,2R)-(+)-1,2-DPEN was successfully bonded to the surface of Wang resin through the amido linkage. Subsequently, the asymmetric Michael addition of acetone to β-nitrostyrene was employed to evaluate their catalytic performance. It was found that the catalyst generated from trimesoyl chloride exhibited much better catalytic behavior than our previously reported catalyst, likely attributed to the multiple hydrogen-bond interaction between β-nitrostyrene and amide group, which made the catalytic transition intermediates more stable. Under the optimal conditions, 76.1% β-nitrostyrene conversion and 93.8% enantioselectivity were obtained. Finally, the generality of this catalyst was examined with Michael additions of acetone to β-nitroolefins and excellent enantioselectivities(91.9% to 99.9%) were achieved.