591-19-5Relevant articles and documents
Pd-doped Ni nanoparticle-modified N-doped carbon nanocatalyst with high Pd atom utilization for the transfer hydrogenation of nitroarenes
Cui, Xueliang,Long, Yu,Zhou, Xia,Yu, Guiqin,Yang, Jin,Yuan, Man,Ma, Jiantai,Dong, Zhengping
, p. 1121 - 1130 (2018)
Palladium (Pd)-based catalysts with maximum utilization of the Pd atoms are attractive for hydrogenation reactions and conserving Pd resources. Herein, the highly dispersed Ni nanoparticle (NP)-modified mesoporous N-doped carbon (Ni/mCN) was successfully prepared by pyrolyzing a mixture of polyacrylonitrile, melamine and Ni(NO3)2·6H2O. Then, the resulting Ni/mCN material with highly dispersed metallic Ni NPs was treated with Pd(AcO)2, and Pd2+ was spontaneously reduced to metallic Pd by the Ni NPs, affording the PdNi NP-based catalyst (PdNi/mCN). The spontaneous reduction process deposits most of the Pd atoms on the surface of the Ni NPs, thus allowing for the maximum utilization of the noble metal Pd. The prepared mesoporous N-doped carbon support can not only provide more surface area to adsorb reaction substrates, but also enhances the accessibility of the active sites of PdNi NPs. The prepared PdNi/mCN nanocatalyst shows a very high catalytic activity for the transfer hydrogenation of nitroarenes using formic acid as the reductant under ambient conditions in aqueous solution, as compared to other Pd-based catalysts, probably because of the highly dispersed PdNi NPs and the maximum utilization of the Pd atoms, as well as the superior structure of mCN. Moreover, the PdNi/mCN nanocatalyst exhibits excellent recyclability and reusability, and the catalytic activity does not obviously decrease after ten reaction cycles. Therefore, we believe that this study should open a new frontier in the preparation of porous N-doped carbon-supported catalysts with maximum utilization of the noble metals for green and sustainable catalysis.
A robust core-shell nanostructured nickel-iron alloy@nitrogen-containing carbon catalyst for the highly efficient hydrogenation of nitroarenes
Zhang, Yaowen,Liu, Chunling,Fan, Guoli,Yang, Lan,Li, Feng
, p. 13668 - 13679 (2018)
Currently, the catalytic selective hydrogenation of nitroarenes to produce aromatic amines is one of the most important key reactions in many fine chemical processes. In particular, non-noble-metal-catalyzed hydrogenation of nitroarenes represents more sustainable chemical processes. Here, we report a new robust and recyclable core-shell nanostructured nickel-iron alloy@nitrogen-containing carbon (NiFe@NC) catalyst and the beneficial effect of alloying Ni with Fe for the above reaction. The key to this synthetic strategy was thermally transforming the Ni-Fe layered double hydroxide (NiFe-LDH)/melamine mixture to form a fixed NiFe@NC nanostructure. A series of characterization results revealed the formation of NiFe alloy nanoparticles (NPs) coated with the NC overlayer. The as-fabricated NiFe@NC catalyst with a Ni/Fe atomic ratio of 3.0 exhibited superior activity for the reduction of the nitro group in o-chloronitrobenzene, with a 99.5% yield of o-chloroaniline under mild reaction conditions. The initial reaction rate over the catalyst was nearly three times that over the monometallic Ni@NC counterpart, and even one-order magnitude higher than that over pristine NiFe-LDH-derived NiFe alloy NPs. The extraordinary activity of NiFe@NC was reasonably attributed to the unique core-shell nanostructure, where both the NiFe alloy core and the NC overlayer shell could construct a significant promotional effect, being beneficial for the selective cleavage of the N-O bond. Recycling experiments indicated that the catalyst could be easily separated and recovered under an external magnetic field and experienced excellent recyclability during seventeen cycles without an obvious loss of catalytic activity. Furthermore, the present catalyst was also highly active for the chemoselective hydrogenation of other substituted nitroarenes bearing different functional groups to the corresponding anilines.
Robust and economic reduction protocol employing immensely stable and leach-proof magnetically separable nanocomposites
Goyal, Ankita,Singhal, Sonal
, p. 91275 - 91294 (2016)
Magnetically recoverable nanocomposites i.e. metal loaded over modified ferrite nanoparticles have been synthesized via a facile three step pathway. Modification of ferrite nanoparticles which serve as the core has been achieved using dopamine hydrogen chloride. Owing to this, introduction of terminal amine groups on the surface of ferrite nanoparticles takes place which provides binding sites for the stabilization of metal nanoparticles providing leach-proof nanocomposites. The synthesized nanocomposites have been characterized using various characterization techniques. Substantiation of the modification of the pristine magnetic ferrite nano particles has been done from the emergence of strong stretching vibration bands of N-H and O-H in the range of 3200-3400 cm-1, N-H stretching band in the range of 1630-1650 cm-1, C-C vibrations of the benzene ring in the range of 1480-1500 cm-1 and C-O stretching vibrations in the range of 1070-1100 cm-1. In the XRD patterns additional peaks corresponding to loaded metals (Cu and Ag) along with peaks corresponding to spinel ferrites have been observed confirming the successful formation of the composite. EDS patterns and FE-SEM elemental mapping confirmed the purity of the samples by displaying the absence of any impurity. Elemental mapping also confirmed the uniform binding of the loaded metals over the surface of modified ferrite nanoparticles. Catalytic efficiency of the synthesized nanocomposites has been explored for the reduction of nitroarenes. Both the Cu and Ag loaded samples exhibited excellent activity and efficient recyclability for the reduction of nitroarenes in the presence of NaBH4 as a reducing agent.
Rhodium nanoparticles supported on 2-(aminomethyl)phenols-modified Fe3O4 spheres as a magnetically recoverable catalyst for reduction of nitroarenes and the degradation of dyes in water
Chen, Tian,Chen, Zhangpei,Hu, Jianshe,Lv, Kexin,Reheman, Aikebaier,Wang, Gongshu
, (2021/06/18)
A magnetic nanostructured catalyst (Fe3O4@SiO2-Amp-Rh) modified with 2-(aminomethyl)phenols (Amp) was designed and prepared, which is used to catalyze the reduction of aromatic nitro compounds into corresponding amines and the degradation of dyes. The 2-aminomethylphenol motif plays a vital role in the immobilization of rhodium nanoparticles to offer extraordinary stability, which has been characterized by using various techniques, including transmission electron microscopy (TEM), thermal gravimetric analyzer (TGA), X-Ray Diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). A variety of nitroaromatic derivatives have been reduced to the corresponding anilines in water with up to yields of 99% within 1?h at room temperature. In addition, the catalyst system is effective in catalyzing the reduction of toxic pollutant 4-nitrophenol and the degradation of MO, MB and RhB dyes. Importantly, this catalyst Fe3O4@SiO2-Amp-Rh can be easily recovered by an external magnetic field because of the presence of magnetic core of Fe3O4, and the activity of Fe3O4@SiO2-Amp-Rh does not decrease significantly after 7 times’ recycling, which indicates that the catalyst performed high reactivity as well as stability. Graphical abstract: [Figure not available: see fulltext.]
NaI/PPh3-Mediated Photochemical Reduction and Amination of Nitroarenes
Qu, Zhonghua,Chen, Xing,Zhong, Shuai,Deng, Guo-Jun,Huang, Huawen
supporting information, p. 5349 - 5353 (2021/07/21)
A mild transition-metal- and photosensitizer-free photoredox system based on the combination of NaI and PPh3 was found to enable highly selective reduction of nitroarenes. This protocol tolerates a broad range of reducible functional groups such as halogen (Cl, Br, and even I), aldehyde, ketone, carboxyl, and cyano. Moreover, the photoredox catalysis with NaI and stoichiometric PPh3 provides also an alternative entry to Cadogan-type reductive amination when o-nitrobiarenes were used.
