Catalysis with palladium colloids supported in poly(acrylic acid)-grafted polyethylene and polystyrene

Abstract

Grafts of poly(acrylic acid) on polyethylene powder (PE-g-PAA) or polystyrene (PS-g-PAA) can be used to support Pd(0) crystallites that function like a homogeneous Pd(0) catalyst in some reactions. These Pd-PE-g-PAA catalysts were active in allylic substitution reactions in the presence of added phosphine ligand. A catalyst analogous to the Pd-PE-g-PAA powder catalyst on polystyrene (Pd-PS-g-PAA) was similarly active for allylic substitution and could also be used in Heck reactions at 80-100°C in N,N-dimethylacetamide (DMA). Analysis of the product solutions for Pd leachate and a correlation of the Pd leaching with product formation in the allylic substitution chemistry for both types of catalysts suggests that the active catalysts in these reactions are leached from the support. In the case of the allylic substitution reaction, external triphenylphosphine and substrate together are required for the chemistry and Pd leaching.Résumé : Les produits de greffage d'acide polyacrylique sur de la poudre de polyéthylène (PE-g-APA) ou de polystyrène (PS-g-APA) peuvent être utilizés comme support de cristallites de Pd(0) qui, dans certaines réactions, peuvent fonctionner comme catalyseur de Pd(0). Ces catalyseurs de Pd-PE-g-APA mis en présence d'un ligand phosphine sont actifs dans les réactions de substitution allylique. Un catalyseur analogue au catalyseur en poudre Pd-PE-g-APA sur du polystyrène (Pd-PS-g-APA) est aussi actif pour la réaction de substitution allylique et il peut aussi être utilizé dans les réactions de Heck, à des températures allant de 80 à 100°C, dans le N,N-diméthylacétamide (DMA). Une analyse des solutions de produits pour rechercher la présence de Pd qui aurait été lessivé ainsi qu'une corrélation du Pd de lessivage avec la formation de produit dans la chimie de la substitution allylique pour les deux types de catalyseur suggère que les catalyseurs actifs dans ces réactions sont lessivés de leur support. Dans le cas de la réaction de substitution allylique, la présence simultanée de la triphénylphosphine externe et du substrat sont requis pour la chimie et le lessivage du Pd.

Organic Polymer Supports for Synthesis and for Reagent and Catalyst Immobilization

“…Ester hydrolysis of 87 afforded poly(acrylic acid) functionalized polystyrene 88 , which was used to immobilize Pd(II) ( 89 ) as a catalyst for hydrogenation reactions. Catalyst 89 could be reduced with H 2 to form 90 , which was an active catalyst for allylic substitution and Heck reactions …”

“…Catalyst 89 could be reduced with H 2 to form 90, which was an active catalyst for allylic substitution and Heck reactions. 134…”

“…In terms of using polyglycerol as a reagent support, a procedure for the conversion of hydroxyl groups of polyglycerol into morpholine groups (134) has been reported (Scheme 26). 182 Alternatively, the hydroxyl groups can be usedtoimmobilizeboronicacids (135)foruseinSuzuki-Miyaura reactions.…”

Bipyridine copper functionalized polymer resins as support materials for the aerobic oxidation of alcohols

“…Although the heterogeneous catalysis approach may suffer from lower catalyst activity and selectivity, the possibility of catalyst recycling and the formation of metal‐free products have favored this technology for many industrial applications today . In the past few years, many polymer supported catalysts have been developed for homogeneous catalysis application, where the catalyst is immobilized on soluble homopolymers or copolymers such as polysiobutylene, poly(acrylic acid) derivatives, poly(ethylene glycol), poly(2‐oxazolines) and various dendrimers . The polymers serve in most cases as a solubilizer for the catalyst in different solvents, from organic solvents to aqueous media, and can be recycled by precipitation in appropriate solvents.…”

Synthesis and Characterization of Semicrystalline Polyethylene‐graft‐Poly(acrylic acid) Copolymers

“…[2] For example, copolymers of ethylene (C 2 H 4 ) and acrylic acid (AA) are employed as adhesives, [3] ion-exchange membrane materials, [4] catalyst support media, [5] and sensors, [6] in addition to serving as blend compatibilizers between polar and nonpolar plastics. [7] Past studies have focused on generating polyolefins containing polar functionalities using a variety of techniques, including: high temperature radical polymerizations, [8] photografting, [9] gamma radiation functionalization, [10] and chemical peroxide grafting.…”