Process for producing stereospecific polymers

摘要

Process for the preparation of bridged metallocene catalysts. A substituted or unsubstituted cyclopentadiene is deprotonated in a polar solvent to form a solution of the corresponding anion species. The solution is then cooled to a temperature within the range of about -10 DEG to -30 DEG C. A minor amount of a solution of substituted fulvene in a polar solvent is added to a major quantity of the solution of anionic substituted or unsubstituted cyclopentadiene. The substituted fulvene is present in the solvent to provide a concentration of less than 2 molal. The substituted fulvene is disubstituted on the terminal (6) carbon atom and may be substituted or unsubstituted on the cyclopentadienyl ring. The resulting mixture is warmed to a temperature within the range of about 0 DEG to 25 DEG C. (room temperature) to produce a bridged cyclopentadienyl ligand. The bridged ligand is then recovered and contacted with a transition metal halide or hydrocarbon compound under reaction conditions sufficient to complex the bridged ligand to produce a bridged metallocene. In the preparation of syndiospecific metallocene catalysts one cyclopentadienyl group is a substituted or unsubstituted cyclopentadienyl ring and the other is a substituted cyclopentadienyl group sterically different from the first ring structure. Here, the cyclopentadienyl compound subjected to the protonation reaction can be a substituted or unsubstituted fluorenyl or indenyl group which is deprotonated and reacted with a 6, 6-dialkyl fulvene.