Studies on the Mechanism of Butadiene–Propene Alternating Copolymerization Using the VO[OCH2C(CH3)3]2Cl–AliBu3 Catalyst

Abstract

The average valence of the vanadium ion in VO[OCH2C(CH3hlzCl-AliBu3 reaction product was measured by a potentiometric method. The number of active centers at-30-80°C was measured by kinetic extrapolation. The active center was assumed to be mainly v+'. By analysis of theIR spectrum of reaction product of two catalyst components, the Al-0-V, Al-0, and V-Cl bonds were confirmed. Probably the active center was v+ 3 having a regular octahedral structure with Al-Cl-V and Al-0-V bridge bonds. Electron donation from butadiene to v+ 3 makes possible a complex formation between them and chain initiation. The propagation is considered to be controlled by coordinating site, a transfer to the monomer was found to be the dominating factor for termination reaction at-30 to-60°C.

Homogeneous Vanadium‐Based Catalysts for the Ziegler—Natta Polymerization of α‐Olefins

“…A mechanism for this reaction was proposed by Shuke and Dingshing. 16 They proposed the catalytically active species to be an aluminium/ vanadium dimer with the vanadium nucleus in the 3+ oxidation state (Fig. 6).…”

Coordination Chemistry and Applications of Vanadium Alkoxides in Catalysis

“…Heterometallic alkyl aikoxides derived from the vanadium alkoxide precatalyst and the alkyl aluminum cocatalysts have been postulated to act as the active catalysts in Ziegler-Natta polymerization with such systems (6). With regard to an approximation to the so far unidentified active species in vanadium-based homogeneous Ziegler-Natta polymerization, alkylation reactions as well as reactions of the vanadium complexes with Lewis bases have been studied.…”