Studies on Alternating Copolymerization of Ethylene and Carbon Monoxide Using Nickel‐Based Catalyst: Cocatalyst and the Polarity of Solvent

Abstract

Polyketone (PK) has attracted wide attention owing to its direct utilization of carbon monoxide, excellent properties, and photodegradation performance. However, the commercialized PK is produced using Pd‐based catalysts, which accounts for the largest part of the production cost. Herein, [Ni(2‐tol)(PPh3)(N,O)] is used as the main catalyst for its high productivity and good tolerance to CO. Effects of the cocatalyst (Ni(COD)2), the aging method in CO atmosphere, and the polarity of solvent are investigated. When Ni(COD)2 is employed as the cocatalyst, the catalytic activity and molecular weight of PK are increased by 29% and 42.6%, respectively. Aging of catalyst system with Ni(COD)2 in CO atmosphere leads to significant decrease in activity and molecular weight, while aging has almost no effect on the copolymerization without Ni(COD)2. Different catalytic mechanisms are proposed for the catalyst system with and without cocatalyst. Furthermore, it is found that the polar solvent (CH2Cl2) significantly increases the activity by 119.2% compared to that in the nonpolar solvent (toluene). However, the thermal stability of the catalyst is much better in toluene. The study on the understanding of catalytic mechanism and improvement of activity will promote the practical application of nonprecious metal catalysts for preparation of PK.

Leveraging natural language processing to curate the tmCAT, tmPHOTO, tmBIO, and tmSCO datasets of functional transition metal complexes

“…These include nickel catalysts with four mixed N, C, O, and P coordinating ligands, i.e., where each ligand type coordinates the metal once; iron dichloride catalysts with tridentate nitrogen coordinating ligands; and ruthenium dichloride catalysts with an NHC ligand and carbene ligand with a chelating oxygen group 101 (i.e., likely derived from the second-generation Hoveyda-Grubbs catalyst 102 ). Surprisingly, all these catalysts have been primarily studied for polymerization: Ni complexes are utilized for ethylene copolymerization with carbon monoxide 103 , Fe complexes are used as catalysts for linear homo-polymerization of ethylene for the synthesis of high-density polyethylene 104 , and Hoveyda-Grubbs catalysts are utilized for ring-opening metathesis polymerization (ROMP) 105 . This highlights how some motifs, despite their limited range of application, have been the focus of a great deal of study as a result of their industrial relevance.…”

Tailor-Made Functional Polyolefins of Complex Architectures: Recent Advances, Applications, and Prospects

“…However, the formation of stable acyl radicals during FRP prevents further chain propagation and makes this approach challenging. In the IP of ethylene–CO monomers, palladium­(II) catalysts are the most prosperous catalytic systems. − Also, nickel complexes can catalyze the coordination copolymerization of ethylene and carbon monoxide. − …”

Recent Advances in the Copolymerization of Ethylene with Polar Comonomers by Nickel Catalysts

“…They could tolerate functional groups such as ester and copolymerize ethylene with functional olefins, even the more challenging 1,1-disubstituted monomer methyl methacrylate (MMA) [76], so these catalysts were extensively studied by different research groups [34,77], including the installation of sterically bulky substituents to block the metal center and/or the design of new electron-donating ligands to reduce the electrophilicity of the metal center. A series of [N,O]-type nickel catalysts based on various new ligands, including βketoiminato [78], five-membered anilinonaphthoquinone [79][80][81], six-membered anilinoanthraquinone [82,83], anilinobenzoic acid methyl ester [84], 2-iminopyridine-N-oxide [85], imidazolin-2-imine [86,87], imine/phosphine-oxide [88,89], and cation-tunable nickel catalysts [90], have been further investigated in the copolymerization of ethylene/norbornene with polar monomers and alternating copolymerization of ethylene and CO [91]. Detailed mechanistic investigations have also been reported to indicate related insertion copolymerization [76].…”