Preparation of palladium nanoparticle catalyst in ionic liquid and its catalytic properties for Heck-Mizoroki reaction

Abstract

A palladium nanoparticle (PdNPs) catalyst was synthesized in halogen-free anion ionic liquid (1-buthyl-3-methylimidazolium lactate, [Bmim]Lac) by a simple chemical approach. The transmission electron microscopy analysis confirmed the presence of highly dispersed PdNPs in [Bmim]Lac with small average particle size distribution from 2.2 to 3.1 nm. The size of the PdNPs increases with decreasing molar ratio of [Bmim]Lac to Pd(OAc)2 and increasing temperature. The activity of PdNPs@[Bmim]Lac catalyst was tested by the Heck-Mizoroki reaction, and the conditions were optimized. The catalyst can efficiently catalyze couplings of various aryl bromides and iodides with different olefins, giving good yields of products under the optimal conditions and be recycled up to six consecutive times.

In situ preparation of graphene oxide supported Pd nanoparticles in an ionic liquid and the long-term catalytic stability for the Heck reaction

“…Ionic liquids (ILs) are considered as green solvents for the Heck reaction due to their excellent nature of formation and stabilization of Pd nanoparticles and the Pd-IL system showed good catalytic activity and stability for the Heck reaction because ILs could x Pd nanoparticles and avoid the agglomeration of Pd nanoparticles to maintain catalytic activity during the reaction process. 31,32 In order to avoid the synthesis of Pd nanoparticles rst and then disperse them into the IL, Cassol et al 33 successfully synthesized Pd nanoparticles in situ in BMI$PF 6 IL by removing dimethylallene and dichloromethane under reduced pressure. Pd nanoparticles were dispersed in the IL with a monomodal size distribution of (1.7 AE 0.3 nm) and showed good catalytic activity for the Heck reaction.…”

The Mizoroki‐Heck Reaction in Tunable Aryl Alkyl Ionic Liquids

“…Without mercury, the yield after three hours is 87 %. The yield after one hour without any mercury is 39 % (see Table 4, entry 2) This could indicate that the reaction is catalyzed via palladium nanoparticles, [72][73][74] whose activity is quenched via the amalgamation with mercury. [75] The reaction therefore might proceed via Pd nanoparticles that are stabilized by the imidazolium cation or the stabilized Pd colloids serve as a reservoir for the active Pd species.…”

Pd nanoparticles entrapped in chitosan superfine fibers as a highly active and stable catalyst for the Mizoroki–Heck reaction

“…However, as the interaction between the solid matrices with palladium species would be greatly decreased after the reduction of Pd 2+ into Pd 0 and the harsh conditions in catalysis would also reduce this interaction, aggregation and leaching of palladium species usually occurs during catalysis, resulting in a decrement of catalytic activity and contamination of the product [8][9][10]. In order to solve these problems, another type of heterogeneous palladium catalyst has been developed by entrapping the palladium species in a solid matrix [11,12]. Besides the physical interaction and chemical complexation of solid matrices, the entrapment is another important factor to prevent aggregation and leaching of palladium species.…”