Homogeneous Single-site Catalysts

VOCl3-AlR3 V(Acac)3-AlEt3 Cr(Acac)3-AlEt3 (1 3) 

2Py AlEt2Cl H20 CoC12, 2Py A1R3 CoC12 2Py A1R3 H20 Co(Acac)2—CS2—A1R3 (1 3 60) 

Co(Acac)3—AlEt3 Co(Acac)3—CS2—A1R3 Ni(Acac)2—AlEt2Cl 

Catalyst (component molar ratio) cis-1,4 (%) trans-1,4 (%) 1,2 (%) Reference 

A particularly high reactivity is exhibited by 4-methyl-1,3-pentadiene in polymerisation with the homogeneous catalysts discussed this monomer is 50-100 times more reactive than butadiene [38,39,43,117], 

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In the late 1980s and in the 1990s, homogeneous metallocene-based Ziegler Natta and related aluminium-free catalysts as well as other non-metallocene-based homogeneous single-site catalysts, which are active in the syndiospecific polymerisation of styrene, were found also to promote the polymerisation of conjugated dienes [16,38 13],... 

The presence of short chain branches, by the addition of one or various comonomers, which could result in intermolecular homogeneous (single-site catalyst) or heterogeneous (multiple-site catalysts) incorporation... 

Insite technology is used for homogeneous single-site catalysts which produce virtually identical molecular structure such as branching, comonomer distribution, and narrow molecular weight distribution (MWD). Solution polymerization yields Affinity polymers with uniform, consistent structures, resulting in controllable, predictable performance properties. ... 

Homogeneous catalysts are very often known as examples of single-site catalysts characterized by complete structural definition and (presumably) complete knowledge of the chemical processes occurring at their catalytic centers. It is a matter of fact that the homogeneous catalysts are molecular complexes constituted by an active core containing a single active atom (of-... 

Table 16.1 Homogeneous catalysts, tethered single-site catalysts, and biphase catalysts for the hydrogenation of aromatic hydrocarbons.

A fist of the metal complexes that have been claimed to generate catalysts for the hydrogenation of carbocyclic aromatic rings is provided in Table 16.1. This list includes homogeneous catalysts, biphase catalysts, and tethered single-site catalysts. 

The advent of homogeneous olefin polymerization based on metallocenes has also ushered in a new era in olefin polymerization. In fact, the recent commercialization of numerous poly(olefins) prepared using metallocene strategies is testament to the importance of this field from both an academic and an industrial viewpoint. One of the main intellectual driving forces is the realization that as a specific example of single site catalysts, these systems are also amenable to... 

Transition Metal Single Site Catalysts-From Homogeneous to Immobilized Systems... 

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