Using Soluble Polymers to Enforce Catalyst‐Phase‐Selective Solubility and as Antileaching Agents to Facilitate Homogeneous Catalysis

Abstract

The enforced phase-selective solubility of polyisobutylene (PIB)-bound Rh II catalysts in biphasic heptane/ acetonitrile mixtures can be used not only to recycle these catalysts but also to minimize bimolecular reactions with ethyl diazoacetate. When cyclopropanation and O À H insertion reactions are carried out with PIB-bound Rh II catalysts either with or without addition of an unfunctionalized hydrocarbon polymer cosolvent, dimer by-product formation is suppressed even without slow syringe pump addition of the ethyl diazoacetate. This suppression of by-product formation is shown to be due to increased phase segregation of the soluble polymer-bound catalyst and the ethyl diazoacetate reactant. These studies also reveal that added hydrocarbon polymer cosolvents can function as antileaching agents, decreasing the already small amount of a soluble polymer-bound species that leaches into a polar phase in a biphasic mixture during a liquid/ liquid separation step.

Block copolymers derived from polyisobutylene oligomers

“…These materials are available with terminal alkene groups that are easily converted into functional groups such as hydroxyl, thiol, azide, ester, amide, and aryl groups – chemistry we and others have used in a variety of applications in catalysis and green chemistry . These materials’ phase selective solubility in alkane solvents like heptane and poly(α‐olefin)s (PAOs) makes these oligomeric hydrocarbon derivatives excellent phase anchors for immobilization of ligands and catalysts . Such functional polyisobutylene derivatives are also useful in that they make otherwise insoluble materials like phthallocyanines, inorganic clusters, and nanoparticles soluble in alkane solvents and in polyolefins .…”

“…PIB oligomers with better defined end group chemistry can be prepared . However, the alkene functionality on commercially available PIB oligomers has been adequate in our past work in designing alkane phase anchored species and the use of commercially available PIB facilitates use of this chemistry by others without expertise in cationic polymerization.…”

“…1 These materials' phase selective solubility in alkane solvents like heptane and poly(a-olefin)s (PAOs) makes these oligomeric hydrocarbon derivatives excellent phase anchors for immobilization of ligands and catalysts. [2][3][4][5][6] Such functional polyisobutylene derivatives are also useful in that they make otherwise insoluble materials like phthallocyanines, 7 inorganic clusters, 8 and nanoparticles soluble in alkane solvents and in polyolefins. 9,10 Here, we explore chemistry to modify the properties of PIB exploring possible routes to block copolymers using the functional groups of commercially available alkene-terminated PIB oligomers as handles to couple polar monomers to these preexisting PIB oligomers.…”

Synthesis of Novel Structure Based Low Generation Branched Salicylaldimine Nickel Complexes and Their Catalysis of Ethylene Oligomerization

“…In our previous work, however, the PAMAM dendrimer catalyst with symmetrical structure had a poor solubility . To our best knowledge, the catalytic activity of catalyst is directly related to its solubility in solvent . In order to overcome the shortcoming of poor solubility of the symmetric dendritic catalyst, we have pioneered synthesized a novel asymmetric dendrimer‐like catalyst in virtue of typical characteristic of post‐metallocene catalyst, which has a novel substituent in the core of the poly (amidoamine) molecule.…”

“…[16] To our best knowledge, the catalytic activity of catalyst is directly related to its solubility in solvent. [17] In order to overcome the shortcoming of poor solubility of the symmetric dendritic catalyst, we have pioneered synthesized a novel asymmetric dendrimer-like catalyst in virtue of typical characteristic of postmetallocene catalyst, which has a novel substituent in the core of the poly (amidoamine) molecule. The solubility of the catalyst increased distinctly due to this structure modify of the asymmetric dendrimer.…”