103826-50-2Relevant articles and documents
Fine tuning of the sheet distance of graphene oxide that affects the activity and substrate selectivity of a Pd/graphene oxide catalyst in the Heck reaction
Saito, Akinori,Yamamoto, Shun-Ichi,Nishina, Yuta
, p. 59835 - 59838 (2014)
The interlayer distance of graphene oxide (GO) in a Pd/GO composite could be tuned using cationic surfactants. The distance becomes larger when a large surfactant is used. The catalytic activity in Heck reactions dramatically improved using the surfactant-modified Pd/GO catalyst. Substrate selectivity could also be improved by adjusting the size of the surfactant to increase accessibility of substrates to the active catalytic centre.
Controlled synthesis of uniform palladium nanoparticles on novel micro-porous carbon as a recyclable heterogeneous catalyst for the Heck reaction
Song, Kunpeng,Liu, Peng,Wang, Jingyu,Pang, Lei,Chen, Jian,Hussain, Irshad,Tan, Bien,Li, Tao
, p. 13906 - 13913 (2015)
Novel dual-porous carbon-supported palladium nanoparticle (Pd NP) catalysts were prepared by sequential carbonization and reduction of microporous organic polymer-encaged PdCl2. The diverse pore structure of microporous organic polymers provides a reservoir for the palladium precursors and prevents Pd NPs from sintering during the carbonization and reaction. The microporous structure has a significant effect on the size and dispersion of palladium NPs. The average size of the Pd NPs (in the range of 4-6 nm) was tuned by changing the pore size distribution and the carbonization temperature. The resulting carbon-supported Pd NPs were characterized by TEM, BET, XRD, and XPS and the Pd loading was calculated by AAS. The encaged Pd NP catalysts prepared by this methodology exhibited outstanding stability and reusability in the Heck reaction and could be reused at least 10 times without appreciable loss of activity.
Palladacycles bearing pendant benzamidinate ligands as catalysts for the Suzuki and Heck coupling reactions
Wu, Kai-Min,Huang, Chi-An,Peng, Kuo-Fu,Chen, Chi-Tien
, p. 9679 - 9687 (2005)
Three pendant benzamidines [Ph-C(NC6H5)-{NH(CH 2)2NMe2}] (1), [Ph-C(NC6H 5)-{NH(CH2Py)}] (2) and [Ph-C(NC6H 5)-{NH(o-C6H4)(oxazoline)}] (3) are described. Reactions of 1, 2 or 3 with one molar equivalent of Pd(OAc)2 in THF give the palladacyclic complexes [Ph-C{-NH(η1-C6H 4)}{N(CH2)2NMe2}]Pd(OAc) (4), [Ph-C{-NH(η1-C6H4)}{N (CH 2Py)}]Pd(OAc) (5) and [Ph-C{-NH(η1-C6H 4)}{N(o-C6H4)(oxazoline)}]Pd(OAc) (6), respectively. Treatment of 4, 5 or 6 with excess of LiCl in chloroform affords [Ph-C{-NH(η1-C6H4)}{N(CH2) 2NMe2}]PdCl (7), [Ph-C{-NH(η1-C 6H4)}{N(CH2Py)}]PdCl (8) and [Ph-C{-NH(η1-C6H4)}{N(o-C6H 4)(oxazoline)}]PdCl (9). The crystal and molecular structures are reported for compounds 1, 3, 5, 6 and 7. The application of these palladacyclic complexes to the Suzuki and Heck coupling reactions was examined.
Dinuclear cobalt complex-catalyzed stereodivergent semireduction of alkynes: Switchable selectivities controlled by H2O
Chen, Ke,Zhu, Hongdan,Li, Yuling,Peng, Qian,Guo, Yinlong,Wang, Xiaoming
, p. 13696 - 13705 (2021/11/16)
Catalytic semireduction of internal alkynes to alkenes is very important for organic synthesis. Although great success has been achieved in this area, switchable Z/E stereoselectivity based on a single catalyst for the semireduction of internal alkynes is a longstanding challenge due to the multichemo- and stereoselectivity, especially based on less-expensive earth-abundant metals. Herein, we describe a switchable semireduction of alkynes to (Z)- or (E)-alkenes catalyzed by a dinuclear cobalt complex supported by a macrocyclic bis pyridyl diimine (PDI) ligand. It was found that cis-reduction of the alkyne occurs first and the Z-E alkene stereoisomerization process is formally controlled by the amount of H2O, since the concentration of H2O may influence the catalytic activity of the catalyst for isomerization. Therefore, this protocol provides a facile way to switch to either the (Z)- or (E)-olefin isomer in a single transformation by adjusting the amount of water.
Mesoporous silica nanospheres supported atomically precise palladium nanocluster: Highly efficient and recyclable catalysts in the reduction of 4-nitrophenol and Heck reactions
Gao, Taiping,Kang, Zhenlu,Zhao, Yining,Zhou, Yilin
, (2021/12/14)
Atomically precise palladium nanoclusters show great potential applications in the field of catalysis owing to its ultrasmall size and precise structure. This work, we report the mesoporous silica nanoparticles (MSNs) supported [Pd3Cl(PPh3)3(PPh2)2]Cl catalysts (denoted as Pd3Cl/MSNs) for the reduction of 4-nitrophenol and Heck coupling reactions of iodobenzene and styrenes. High uniform MSNs, with average diameter ≈110 nm, were prepared by sol–gel method, followed by Pd nanoclusters immobilization into the pore of MSNs. The MSNs supported Pd nanoclusters were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), and diffuse reflectance optical spectrum. The results indicated that Pd3Cl nanoclusters after immobilized into the pores of MSNs are intact and possess good dispersibility. The catalytic performance of as-prepared nanocomposites was evaluated by the reduction of 4-nitrophenol and Heck reactions. The 4-nitrophenol could be completely conversion to 4-aminophenol within 6?min. Meanwhile, the as-prepared Pd3Cl/MSNs exhibit excellent catalytic performance in the Heck reactions between iodobenzenes and styrenes. The high catalytic activity of Pd3Cl/MSNs could be attributed to the large surface area and unique geometric structure of as-prepared Pd nanoclusters. More importantly, the catalysts could be easily recycled by centrifugation and shows excellent reusability.
