Cascade Reactions in Polymeric Nanoreactors: Mono (Rh)‐ and Bimetallic (Rh/Ir) Micellar Catalysis in the Hydroaminomethylation of 1‐Octene

Abstract

The concept of micellar catalysis was transferred to the hydroaminomethylation of 1‐octene with N,N‐dimethylamine. In the first series of experiments a rhodium(I) complex with amphiphilic triphenylphosphane functionalized poly(2‐oxazoline)s as macroligand was applied as catalyst. Results obtained under standard hydroformylation conditions (T = 100 °C, p = 50 bar) were not satisfying with regard to activities and selectivities of the hydroaminomethylation reaction. Rising the temperature to 150 °C increased the yield of amine to 22% with a corresponding n/iso selectivity of 7.5 and a TOF number of 461 h−1. Best results were obtained by applying a dual Rh/Ir catalyst within the polymeric micelles leading at lower temperature of 130 °C to an amine yield of 24% with a corresponding n/iso selectivity of 11 and TOF numbers of about 600 h−1.magnified image

Poly(2‐oxazoline)s based on fatty acids

“…Block copolymers functionalized with a catalytic ruthenium(II) complex were successfully applied for aqueous ring-closing metathesis [61] as well as for the formation of poly(acetylene) latex particles [62]. In addition, a rhodium functionalized block copolymer was prepared and subsequently applied for micellar catalysis of hydrogenation reactions [63], hydroamino-methylation reactions [64] as well as hydroformylations [65,66]. For the latter hydroformylation reactions triphenylphosphine decorated block copolymers were prepared that were subsequently applied for micellar catalysis in a biphasic system, i.e., the micellar catalysts are present in the aqueous phase while the substrate and product are present in the lipophilic phase as depicted in Figure 7.…”

Catalytic polymeric nanoreactors: more than a solid supported catalyst

“…[6] The covalent immobilization of transition metal catalysts (Rh, Ir, or Pd) within the hydrophobic core increased the local concentration of the catalyst in the reaction. [34,35] The hydrophobic substrates were dissolved in the micellar core, where the catalyst was also located, allowing the transformations to be carried out in an overall aqueous environment, significantly increasing the reaction rates compared with the water-soluble homopolymer counterparts. [36] However, the leaching of the catalyst could not be avoided therefore the recyclability of this polymeric systems was limited.…”

“…Unfortunately, conditions optimized for one reaction were not favorable for the next one, probably due to the competition of more than one substrate for the metal center and the deactivation of the catalyst. [34] Polymeric stars A similar but simpler approach to obtain stable polymeric nanoreactors is to synthesize unimolecular micelles. The facile synthesis and tunable composition of star polymers makes them an attractive alternative to the widely studied dendritic systems or other cross-linked micelles.…”

Domino Reactions Triggered by Hydroformylation

“…Webersikirch investigated the possibility of using a tailor-made dual heterogeneous Rh/Ir systems to catalyze HAM of terminal olefines, Rh being suitable for the HF and Ir for the selective reduction of the enamines (Fig. 2) [19]. Despite the wonderful results obtained using Rh triphenylphosphine functionalized poly(2-oxazoline) block polymers in the HF of octene, under HAM conditions a mixture of the aldehyde, enamine, and the expected product was observed.…”