Reactivity of Phosphino‐naphtholate Nickel Complexes and Their Catalysis of Copolymerization with Polar Monomers

• Published in: ChemCatChem 2022-03, Vol.14 (5), p.n/a
• Main Authors: Wang, Xu‐ling, Zhang, Yan‐Ping, Pan, Li, Wang, Fei, Luo, Shui‐yuan, Li, Yue‐sheng
• Format: Article
• Language: English
• Subjects: Acrylics; Catalysis; coordination and insertion; Copolymerization; in-situ reaction; Insertion; Monomers; neutral nickel catalyst; Nickel; olefin polymerization; polar monomer; Polyethylenes; Polymethyl methacrylate; Polyolefins; Reactivity
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.202101736

Coordination‐insertion copolymerization of ethylene with polar monomers can directly provide value‐added functionalized polyolefins. Studies on the reactivity of catalysts toward polar monomers can help understand the copolymerization process and then tune the polymerization strategically. In this contribution, the reactivity picture of 2‐diphenylphosphonyl‐8‐phenylnaphthol nickel complex toward fundamental polar monomers was explored by stoichiometric reactions. The insertion rates are in the order of methyl acrylate (MA)>n‐butyl acrylate (BA)>N, N‐dimethylacrylamide (DMAA)>methyl methacrylate (MMA)>vinyl triethoxysilane (VTEoS)>N‐vinyl‐pyrrolidinone (NVP). Acrylic derivatives of MA, BA and DMAA with electron‐withdrawing group favor 2,1‐fashion while non‐acrylic NVP with electron‐donating group prefers 1,2‐fashion. Notably, the 1,1‐disubstituted MMA and bulky VTEoS perform a preferential 1,2‐insertion accompanying by 2,1‐insertion in the percentage of 82 : 18 and 62 : 38, respectively, because of the stronger steric effect. These insights correlate to the copolymerization of polar monomers with ethylene. Linear functional polyethylene with in‐chain and terminal incorporation of BA, DMAA or VTEoS is afforded at a high activity. Olefin polymerization: Phosphino‐naphtholate neutral nickel catalyst performed an excellent reactivity toward electron‐deficient acrylic derivatives (BA, MMA, DMAA) and electron‐rich vinyl monomers (VTEoS, NVP). Notably, BA and DMAA displayed higher insertion rates and they favor 2,1‐insertion into the Ni−CH3 bond while the bulky MMA, VTEoS and electron‐rich NVP prefer 1,2‐fashion. The reactive polar monomers were copolymerized with ethylene at high activities.