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Kaminsky catalyst
A Kaminsky catalyst is a catalytic system for alkene polymerization discovered in 1980. Kaminsky catalysts are based on metallocenes of group 4 transition metals with methylaluminoxane (MAO). These catalysts are a type of Ziegler-Natta catalyst, but they are homogeneous and show extremely high activity for polymerization of olefins such as ethylene and propylene. In addition, the use of chiral metallocenes that have bridged cyclopentadienyl rings has made possible highly stereoselective (or stereoregular) polymerization of α-olefins. For example, by using metallocene 1 for polymerization of propylene, atactic polypropylene is obtained, while ''C''2 symmetric metallocene 2 and ''C''s symmetric metallocene 3 catalytic systems produce isotactic polymer and syndiotactic macromolecule, respectively.
Kaminsky catalysts are very attractive from the industrial, organometallic, and polymer science points of view, and they are studied to improve their activity and to achieve high tacticity and high molecular weight of the produced polymers.
==Synthesis==
MAO undergoes a rapid ligand exchange with a metallocene dichloride. This produces a metallocene methyl and dimethyl aluminum compound. After this ligand exchange either a chlorine or methyl is abstracted from the metallocene by one of the aluminum centers in MAO. This process of abstraction produces a metallocene cation as well as a MAO anion. The resultant alkylated metallocene is the active center.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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