Ziegler-Natta catalysts homogeneous

Muhlhaupt R, Fischer D, JUngling S (1993) Donor- and acceptor-modified metallocene-based homogeneous Ziegler-Natta catalysts. Makromol Chem Macromol Syp 66 191-202... 

Idemitsu A process for making C6-C18 a-olefins from ethylene, catalyzed by a modified homogeneous Ziegler-Natta catalyst containing a zirconium chloride. Developed by the Idemitsu Petroleum Company in 1988. 

The polymerization of a-olefins, promoted by homogeneous Ziegler-Natta catalysts based on bis(cyclopentadienyl)titanium(IV) or analogous zirconium compounds and aluminum alkyls, occurs simultaneously with a series of other reactions that greatly complicate the kinetic interpretation of the polymerization process (see Scheme 3). 

C to form the dinuclear (butadienyl)zirconium system 120. Treatment with B(C6F5)3 leads to the formation of a mono-addition product (121), even in the presence of excess borane. Complex 121 (Scheme 40) shows only a marginal ethene polymerization activity. This led to the notion that such formation of dimeric zirconium complexes might represent desactivation pathways in homogeneous Ziegler-Natta catalyst chemistry.125... 

Homogeneous Ziegler-Natta catalysts of the classic type, capable of olefin polymerisation, are usually derived from reactions of a hydrocarbon soluble transition metal compound with an alkylmetal compound in a hydrocarbon solution (heptane, hexane, toluene). However, the polymer formed in the presence of such soluble Ziegler-Natta catalysts is very often precipitated during polymerisation. 

It may be interesting, in connection with the ethylene/propylene copolymers mentioned above, to present here some homogeneous Ziegler-Natta catalysts formed by soluble complexes of titanium and magnesium chlorides with alkyl phosphates as catalyst precursors and alkylaluminium compounds as activators (TiCl4)x.(MgCl2)r [0=P(0Bu)3]3-A1(/-Bu)3 and Cl3TiOMgCl-[0 = P(0Bu)3]3- A1(z -Bu)3 (Al/Ti molar ratio of ca 10 1). These catalysts have been used for random ethylene/propylene copolymerisation [73],... 

In the case of olefin polymerisation with homogeneous Ziegler-Natta catalysts, especially with single-site (metallocene) catalysts, the kinetic analysis may become simpler than in the case of polymerisation with heterogeneous catalysts, and in some instances can serve as a very useful tool for uncovering the true polymerisation mechanism [30,243],... 

Typical values of comonomer relative reactivity ratios in ethylene/propylene copolymerisations run with various heterogeneous and homogeneous Ziegler-Natta catalysts are listed in Table 3.5 [30, 72, 454]. 

Miller, S. A. and Waymouth, R. M., Stereo- and Enantioselective Polymerisation of Olefins with Homogeneous Ziegler-Natta catalysts , in Ziegler Catalysts, Springer-Verlag, Berlin, 1995, pp. 441-454. 

Give the structure and stereochemical designation of all possible poly(a-olefin)s that could, in principle, be obtained by stereospecific polymerisation. Are they all likely to be obtainable in practice (with heterogeneous and homogeneous Ziegler-Natta catalysts) ... 

Gao, W. and Cui, D.M. (2008) Highly cis-1,4 selective polymerization of dienes with homogeneous Ziegler-Natta catalysts based on NCN-pincer rare earth metal dichloride precursors. Journal of the American Chemical Society, 130, 4984. 

The thermodynamics of the reaction of the ethylene molecule with the Cp2TiClMe/AlClMe2 system, as a model for olefin polymerization with homogeneous Ziegler-Natta catalysts, has been investigated using DFT calculations.1237... 

Other well known homogeneous Ziegler-Natta catalysts include derivatives of V and organoaluminum compounds... 

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