Heck Reaction Catalyzed by Nanosized Palladium on Chitosan in Ionic Liquids

Abstract

Palladium nanocolloids supported on chitosan behave as very efficient heterogeneous catalysts in the Heck reaction of aryl bromides and activated aryl chlorides in tetrabutylammonium bromide as solvent and tetrabutylammonium acetate as base. Only 15 min is required to convert bromobenzene or p-nitrochlorobenzene into cinnamates. The efficiency of this catalyst is due to the stabilization of Pd colloids by the solvent and to a very fast PdH neutralization by the base. In contrast, no reaction occurs when utilizing imidazolium-based ionic liquids. The stability of the catalyst allows an extensive recycle in the coupling of iodoaromatics with butyl acrylate.

Revisiting Heck–Mizoroki reactions in ionic liquids

“…62 For example, Calò and co-workers pointed out that Pd nanoparticles easily prepared just by adding palladium acetate to a mixture of tbab in the presence of tetrabutylammonium acetate (tbaa) as the base are highly efficient in the coupling of a wide range of olefins and aryl halides, namely aryl chlorides. [63][64][65][66] This work has been the subject of an excellent review by the authors. 44 Another important contribution concerning the role of palladium nanoparticles in Heck reactions in IL is due to Dupont, where it was demonstrated that imidazolium ionic liquids can be used to investigate the shape and size of colloidal nanoparticles.…”

“…Based on their previous results 44,65,[68][69][70] that Pd colloids can promote the C-Cl activation, Nacci et al 71 reported the use of Pd nanoparticles obtained in ILs and water as catalysts in onepot sequential Heck-Mizoroki and Suzuki coupling reactions using bromo-chloroarenes or bromo-iodo-chloroarenes. The strategy allowed to prepare extended p-systems having a multisubstituted arene with different motifs as the basic skeleton.…”

Silica-Supported Palladium-Catalyzed Hiyama Cross-Coupling Reactions Using Continuous Flow System

“…[34][35][36] A supporting material with smaller particles is known to be better than that with larger particles due to its larger surface area of catalyst. However, very small particles are not suitable as a packing material in the continuous flow system because of their plugging tendency and high-pressure drop.…”

Chitosan capped Silver nanoparticles used as Pressure sensors

“…The primary challenges in this regard are the maximization of sage of environmentally friendly materials in the generation of nanoscale based products. Among the many products that have been developed, polymer-metal nanoparticle composites seem to receive special attention because of their application potential in sensors [1,2], actuators [3], electrodes for fuel cells [4], supported micro-heterogeneous and heterogeneous catalyses [5,6,7,8] and in optical and optoelectronic devices [9,10,11] Chitosan, a novel biopolymer, is a product of deacetylation of chitin, which is the second most abundant natural polymer in the world after cellulose. The biocompatibility and antibacterial properties of chitosan and its being an environmentally friendly polyelectrolyte makes it appealing for several applications such as water treatment [12], novel fibers for textiles [13], photographic paper [14,15], biodegradable films [16,17], biomedical devices and microcapsule implants for controlled release in drug delivery [18,19,20] In recent years polymers have attracted considerable attention due to their importance in emerging technologies [21,22,23,24,25].…”