No abstract

New imidazolyl‐functionalized ordered mesoporous cross‐linked polymers were prepared by the copolymerization of the ionic liquid 3‐benzyl‐1‐vinyl‐1H‐imidazolium bromide with divinylbenzene as the cross‐linker and azobisisobutyronitrile as the radical initiator in the presence of O‐silylated SBA‐15 as the hard template. The materials were characterized by N2 adsorption–desorption analysis, TEM, thermogravimetric analysis, elemental analysis, and FTIR spectroscopy. The material, which benefits from the use of entrapped ionic liquid in the prepared polymer matrix in combination with its ordered mesoporous structure, is an excellent environment for the stabilization of highly dispersed Pd nanoparticles to result in a recyclable catalyst system with a significant activity in the Heck coupling reaction of aryl halides. The presence of well‐distributed imidazolium functionalities in the polymeric framework might be responsible for the relatively uniform and nearly atomic scale distribution of Pd nanoparticles throughout the mesoporous structure and the prevention of Pd agglomeration during the reaction, which results in high durability, high stability, and good recycling characteristics of the catalyst. Although our catalyst system operates in a homogeneous pathway, it is also very stable and recyclable.

An imidazolium based ionic liquid bearing triethylene glycol (TEG) tag was employed as a functional monomer together with divinylbenzene to prepare a novel hydrophilic mesoporous polymer containing ionic liquid functionalities via nanocasting method using SBA‐15 as a hard template. The material was characterized using transmission electron microscopy (TEM), N2 sorption analysis, thermo‐gravimetric analysis (TGA), Fourier‐transform infrared spectroscopy (FT‐IR), elemental analysis (CHN), solid‐state NMR spectroscopy and contact angle measurement. It was found that the hydrophobic/hydrophilic properties of initial template, stepwise addition of monomers and initiator as well as amount of carrier solvent are of the important parameters in preparation of the polymer with uniform pore structure. Benefited from the combined properties such as incorporation of ionic liquid within the pore system of a flexible organic matrix together with its hydrophilic character, the material was found as an appropriate support to generate highly dispersed and very small size of Pd nanoparticles inside the pores. The prepared catalyst in this way, demonstrated outstanding activity, recyclability and high durability in the Suzuki cross‐coupling reaction of varied aryl halides with boronic acids in water as a green reaction medium. The beneficial role of imidazolium ionic liquid in the formation of small and highly active Pd nanoparticles was confirmed with comparative experiments.

In recent years ionic liquids (ILs) have attracted much interest because of their widespread use in various fields. Several trimerization and oligomerization catalysts have been evaluated in ILs with different organic–inorganic hybrid structures. High catalytic activity and selectivity, easy product separation, and recycling of the catalyst are the advantages of a biphasic catalyst system compared to the homogeneous catalysts. In this study, the influence of IL counter‐anions on activity and selectivity of the ethylene trimerization catalysts based on Cr‐SNS‐R was investigated. All synthesized materials were characterized using Fourier‐transform infrared spectroscopy, 1H NMR, 13C NMR, UV–Vis. spectroscopy, thin‐layer chromatography, and elemental analysis (CHNS). In ethylene trimerization reaction, the dodecyl substituent in the SNS ligand exhibited better activity and selectivity than the butyl substituent. The results revealed that the presence of BF4− as a counter‐anion in the IL led to an increase in activity and selectivity compared to Br− and I− counter‐anions. It was found that the BF4− counter‐anion plays a conclusive role in the development of 1‐hexene activity and selectivity to a maximum amount of 71,132 g1‐C6/(gCr × h) and more than 99%, respectively. Finally, the catalyst was reused thrice without losing its 1‐hexene selectivity.

In this study, we improved the catalytic performance of manganese porphyrin encapsulated HY zeolite for alkene epoxidation reaction. For this purpose, Manganese tetra pyridyl porphyrin encapsulated into modified dealuminated Y zeolite (MnTPP-MDAZY) was synthesized using zeolite template synthesis method. This heterogenized catalyst was characterized by FT-IR, UV-Vis, XRD and atomic absorption spectra (AAS) technique. Catalyst loading was 0.263 mmol/g support. In this way, high catalyst loading is probably related to the decrease of the size of metalloporphyrin and the post-synthesis treatment. The latter one causes the increase of the diameter of the mesoporous structure as a result of the dealumination of zeolite with EDTA treatment. High catalyst loading efficiently enhances the epoxidation of alkenes.