Neutral Ni(II) Catalysts Based on Maple-Lactone Derived [N,O] Ligands for the Polymerization of Ethylene

Abstract

This paper describes the synthesis of neutral nickel(II) catalysts for the polymerization of ethylene. A series of 2-(arylamino)-5-methylcyclopent-2-en-1-one (aryl = 2,6-diisopropylphenyl, 2,4,6-trimethylphenyl, 3,5-dimethylphenyl, and 4methylphenyl) proligands, derived from the condensation of aryl amines with maple lactone, were synthesized as their keto-enamine tautomers. Deprotonation with NaH gave their respective sodium imino-enolate salts, which underwent salt metathesis with Ni(II) precursors to give square planar [Ni(Ar)(κ 2 -imino-enolate)(PPh 3 )] (Ar = Ph, ortho-tolyl) complexes containing 5-membered [N,O] chelates. Precatalysts with N-Dipp (Dipp = 2,6-diisopropylphenyl) substituents were found to exhibit moderate activity in the polymerization of ethylene when using B(C 6 F 5 ) 3 or [Ni(cod) 2 ] (cod = 1,4-cyclooctadiene) as coactivators, producing polymers with a high molecular weight, as determined by GPC. The reaction was found to be highly dependent on temperature, with the catalysts most active at 80 °C. Differences in polymer structure were also found when using B(C 6 F 5 ) 3 or [Ni(cod) 2 ] as the cocatalyst, with [Ni(cod) 2 ] producing a more highly branched polymer. Reducing the steric bulk at the N substituent of the ligand led to inactive species.

Synthesis and pyrolysis of methyl cyclopentenolone succinate diester

“…4 Methyl cyclopentenolone mainly exists in the beech tar 5 and coffee beans, 6 which favours to release of a coffee-like aroma after high-temperature pyrolysis. Methyl cyclopentenolone derivatives has been widely employed in a range of applications in food, 3 medicine, 7 the chemical industry 8,9 and other fields. For example, methyl cyclopentenolone is applied as raw material to prepare inhibit NF-κB inducing kinase (NIK) and pharmaceutical compositions, which can be contributed for the prevention or treatment of cancer.…”

“…For example, methyl cyclopentenolone is applied as raw material to prepare inhibit NF‐κB inducing kinase (NIK) and pharmaceutical compositions, which can be contributed for the prevention or treatment of cancer 7 . Methyl cyclopentenolone can also be used to synthesize a neutral nickel (II) catalyst for ethylene polymerization 8 . 2‐Furylmethyl ketone (2‐FMK) has attracted the wide attention of researchers because it can be used as a higher‐grade fuel source.…”

“…7 Methyl cyclopentenolone can also be used to synthesize a neutral nickel (II) catalyst for ethylene polymerization. 8…”