Synthesis of novel bis(β-enaminoketonato)titanium catalyst with high activity and excellent ability to copolymerize olefins

摘要

A new titanium complex [PhN=C(Ph)CHC(CF _3)O] _2TiCl _2(2a), with an asymmetric β-enaminoketonato [N,O] ligand, has been synthesized and fully characterized. With modified methylaluminoxane as a cocatalyst, the behaviors of ethylene polymerization, and ethylene/α- olefin and ethyleneorbornene copolymerization have been explored in detail. Relative to its regioisomer 2b([PhN=C(CF _3)CHC(Ph)O] _2TiCl _2), the present catalyst exhibits significant predominance. The catalytic activity in 2a-catalyzed homo- and copolymerization are much higher than those in 2b-catalyzed(co)polymerization. Furthermore, compared with 2b, catalyst 2a possesses an obviously stronger ability towards copolymerization, due to a wide coordination space caused by exchanging the position of the phenyl group and trifluoromethyl group on the framework.