Efficient and Recyclable Catalyst of Palladium Nanoparticles Stabilized by Polymer Micelles Soluble in Water for Suzuki-Miyaura Reaction, Ostwald Ripening Process with Palladium Nanoparticles

Abstract

The Suzuki-Miyaura cross-coupling reaction of ArX (I, Br) with Ar¢B(OH) 2 , catalyzed by Pd-containing water-soluble micelle formed by PS-PEO copolymer and N-cetylpyridinium chloride as a surfactant, was studied in water and methanol. The reaction was performed under mild conditions (temperature up to 50°C) and the catalyst can be recycled (5 runs) by ultrafiltration without any loss of its catalytic activity. The phenomenon was observed, consisting in growing Pd-nanoparticle size because the small nanoparticles dissolve to form larger nanoparticles in the course of reaction as well as in the presence of the only reagent, ArI. In the latter case, additionally, the formation of very small, not completely dissolved Pd nanoparticles, obviously having a high catalyst activity, is observed. This observation, together with the catalyst activity data might have an implication for a leaching mechanism for the studied catalytic system.

Hydroxy- and alkoxycarbonylation of aryl iodides catalyzed by polymer-supported palladium

“…K 2 PdCl 4 , H 2 PdCl 4 [12] and palladium catalysts used were prepared according to known procedures [8,9]. Solvents were purified by standard techniques.…”

Application of “Boomerang” Linear Polystyrene-Stabilized Pd Nanoparticles to a Series of C-C Coupling Reactions in Water

“…Unfortunately, heterogenization of metal nanoparticles decreases catalytic activity. Additionally, the recovery and reuse of metal nanoparticles have been difficult to achieve due to a significant loss and/or morphology changes of the metal nanoparticles during reaction and workup [13][14][15]. Since leaching of soluble metal species from the support is a major cause of catalyst deactivation, efforts have been reported to develop an effective support that prevents leaching of metal species [16][17][18][19].…”

“…On the other hand, metal nanoparticles possess high catalytic activity in water [11][12][13][14][15][16][17][18][19] and have been used not only as semi-heterogeneous catalysts, but also as semi-heterogeneous supports [20][21][22][23]. Unfortunately, heterogenization of metal nanoparticles decreases catalytic activity.…”

Suzuki reaction: mechanistic multiplicity versus exclusive homogeneous or exclusive heterogeneous catalysis

“…Now it is quite clear that there is no consensus on the nature of the catalysis of this reaction (see review 2 published in 2006 and references cited therein). Analysis of the literature for the last two years indicates that some researchers advance the hypothesis of a homogeneous catalysis mechanism [3][4][5][6][7][8][9][10][11] while the others suggest a heterogeneous mechanism. [12][13][14][15][16][17][18] It is worth mentioning that the most convincing evidence is for the homogeneous mechanism of the Suzuki reaction.…”

“…[12][13][14][15][16][17][18] It is worth mentioning that the most convincing evidence is for the homogeneous mechanism of the Suzuki reaction. [3][4][5]10,11 But mechanistic studies of the reactions never provide absolute unequivocal evidence for any mechanism and it makes judging only possible about the relative probability; a set of different experimental approaches (as wide as possible) to perform the mechanistic research. In this work a new approach to the Suzuki reaction was applied for the first time: i.e.…”