Double-Decker-Type Dipalladium Catalysts for Copolymerization of Ethylene with Acrylic Anhydride

Abstract

Dipalladium complex with a macrocyclic ligand having two diimine sites catalyzes copolymerization of ethylene with acrylic anhydride to afford the copolymer containing the repeating unit from acrylic anhydride. The obtained copolymer contains the cyclic and acyclic anhydride groups in high content (up to 5.7 mol %) in the main chain. It is contrasted with that the monopalladium complex with the diimine ligand catalyzes the reaction to yield the copolymer having the polar group at the end of branches with lower content (0.8 mol %). Decreased ethylene pressure of the reaction using the dipalladium catalyst results in increase in the polar comonomer unit content. Methanolysis of the copolymer takes place smoothly to give the polymer with both carboxylic acid and ester groups in the polymer chain.

A continuing legend: the Brookhart-type α-diimine nickel and palladium catalysts

“…In addition, C43b catalyzed copolymerization of E with acrylic anhydride to afford the copolymer containing the repeating unit from acrylic anhydride. 124 These studies clearly indicated that structures of α-diimine ligands can strongly influence the polymerization processes.…”

“…66 The 1-hexene polymerization results indicated that increasing ligand sterics led to enhancement of the chain straightening phenomenon. 65 The comonomer incorporations and copolymer microstructures can also be tuned in C8a-c catalyzed ethylene copolymer- [122][123][124] ization of methyl acrylate. These palladium catalysts also generated various branched carboxylic acid-functionalized polyolefins with better control over material properties.…”

“…21) bearing a macrocyclic ligand. [122][123][124] In ethylene polymerization, dinuclear complex C43b displayed higher activity compared with the corresponding mononuclear catalyst and C43a. The polyethylenes obtained by C43a and C43b were less branched than those made with a mononuclear one.…”

“…In the process of exploring various Brookhart catalysts, various olefinic monomers have been polymerized and copolymerized. 27,31,[125][126][127] The applicable monomers have also been rapidly growing to include linear 128,129 and branched 130,131 α-olefins, cycloalkyl substituted α-olefins, 132-136 cycloolefins, 137 dienes, 138 trienes, 139,140 internal olefins, [141][142][143][144] norbonene type monomers, [101][102][103][104] and different polar comonomers. 3,27,28 It should be noted that the continuous interest in Brookhart-type catalysts largely originates from their capabilities in copolymerizations of olefins with polar functionalized comonomers.…”

Olefin Polymerization and Copolymerization Catalyzed by Dinuclear Catalysts Having Macrocyclic Ligands

“…The dipalladium complex Pd 2 (L3b) was also effective for the copolymerization of ethylene with acrylic anhydride (ethylene 1 MPa, [methyl acrylate]/[Pd] 420) (Scheme 9). 38 In this copolymerization the dipalladium complex Pd 2 (L3b) again shows higher activity, and affords higher molecular weight copolymer (M n 26,400) than the monopalladium complex Pd(L6b) (M n 3,290). The degree of branching of the copolymer formed by the dipalladium complex Pd 2 (L3b) (58 branches/1,000 C) was lower than for the monopalladium complex Pd(L6b) (103 branches/1,000 C), and it contained 2.6 mol % of the repeating unit from acrylic anhydride.…”