Palladium chloride anchored on organic functionalized MCM‐41 as a catalyst for the Heck reaction

Abstract

Palladium chloride was grafted to amino-functionalized MCM-41 to prepare heterogeneous catalysts. XRD, N 2 adsorption-desorption isotherms, IR, 13 C and 29 Si cross-polarization magic-angle spinning NMR spectroscopy and XPS techniques were employed to characterize the catalytic materials. The heterogeneous palladium catalyst exhibited excellent catalytic activity for the Heck vinylation of iodobenzene with methyl acrylate, giving 92% yield of methyl cinnamate in the presence of Nmethylpyrrolidone (NMP) and triethylamine (Et 3 N). The stability of the heterogeneous catalyst was also studied in detail. The catalytic tests showed that the palladium leaching correlated to solvent, base and palladium loading. The heterogeneous catalyst exhibited excellent stability towards loss of activity and palladium leaching was not observed during six recycles in the presence of toluene and Na 2 CO 3 .

An efficient and new protocol for the Heck reaction using palladium nanoparticle‐engineered dibenzo‐18‐crown‐6‐ether/MCM‐41 nanocomposite in water

“…The result reveals the presence of Pd nanoparticles on the silica surface with characteristic peaks at 2 θ of 40.0°, 46.9°, 67.9° and 80.1° corresponding to [111], [200], [220] and [311], respectively, and the strongest peak of the XRD pattern corresponding to the structure of silica phase. This observation confirms the presence of metallic Pd particles on the mesoporous MCM‐41 surface . The low‐angle XRD pattern of the MCM‐41‐Crown.Pd nanocomposite (Figure b) shows one peak at 2 θ = 2.6°, corresponding to the [100] plane, which is characteristic of a hexagonal pore system.…”

“…The Pd‐catalysed cross‐coupling reactions, especially Heck arylation of olefins with aryl halides, are simple, efficient and versatile routes to the formation of carbon–carbon bonds commonly used in modern organic synthesis . For excellent performance of Pd‐catalysed processes, use of high‐activity Pd catalysts and green reaction conditions are two important strategies for the design of new heterogeneous Pd catalytic systems …”

Preparation and characterization of palladium immobilized on silica‐coated Fe3O4 and its catalytic performance for Suzuki reaction under microwave irradiation

“…The band presenting at 1630 cm −1 belongs to the bending vibration of adsorbed water . The asymmetric stretching vibration and symmetric stretching vibration of Si―O―Si are situated at 1088 and 799 cm −1 , respectively . In addition, the band at 565 cm −1 in the IR spectra of Fe 3 O 4 , Fe 3 O 4 @SiO 2 and Pd/Fe 3 O 4 @SiO 2 is attributed to the vibration of Fe―O bond .…”

“…The yield of biphenyl then significantly dropped with further increase in Pd loading; only 85.3% yield of biphenyl was given in the presence of 14.8 wt% Pd loading. It is possibly ascribed to the aggregation of the active sites with higher Pd content, leading to poor dispersion and thus giving the negative effect on the catalytic performance as well as reaction …”

Synthesis of well-ordered MCM-41 containing highly-dispersed NiO nanoparticles and efficient catalytic epoxidation of styrene

“…The band at 3445 cm −1 observed in all samples are ascribed to the symmetrical stretching vibration of -OH groups on the surface of MCM-41 and the band at 1627 cm −1 is assigned to the bending vibration of adsorbed water. 32 The bands at 1083 and 808 cm −1 are related to the asymmetric stretching vibration and symmetric stretching vibration of Si-O-Si in the framework of silica, 33 respectively. Additionally, the absorption bands at 976 cm −1 confirmed the presence of silanol group Si-OH and its symmetric stretching vibration; 34 moreover, the intensity of the absorption peaks showed a decreasing trend with increasing loading of nickel in these samples, suggesting the decreasing of surface Si-OH in the samples.…”