Patent ID: 6107501
Filing Date: 2000-08-22
Classification: C07F,Y10S

Abstract:
Method of synthesizing stereorigid metallocene having chiral center and enriching its rac isomer content, comprising steps of:a) selecting desired cyclopentadienyl ring-containing compound capable of forming metallocene with chiral center and dissolving compound in solvent suitable for dissolving such compound provided that solvent is not alkali metal-reactive;b) contacting mixture of a), under suitable conditions of mixing and temperature for sufficient time to react, with suitably reactive alkyl alkali metal compound;c) dissolving solid created in b) with sufficient solvent suitable for dissolving solid;d) contacting solution created in c) with suitable halogenated compound with which bridge between two cyclopentadienyl ring-containing compounds may be formed, under suitable conditions of mixing and temperature for sufficient time to react;e) removing solvent, and, optionally, removing residual starting cyclopentadienyl ring-containing compound;f) dissolving solid created in e) in solvent suitable for dissolving this solid and contacting with suitable alkyl alkali metal compound under suitable conditions of temperature and mixing for a sufficient time to react;g) removing solvent, and, optionally, removing residual starting cyclopentadienyl ring-containing compound;h) slurrying or suspending solid created in g) with sufficient solvent suitable for slurrying or suspending this compound;i) contacting slurry or suspension of h) with sufficient suitable metal tetrahalide under suitable conditions of temperature and mixing for a sufficient time to react;j) removing residual alkali halide from solid created in i);k) removing solvent from solid of j);l) enriching rac metallocene isomer by suspending solid of k) in solvent suitable for solvating non-rac isomers in suitable amount under suitable conditions of temperature and mixing for time sufficient to solvate non-rac isomers;m) removing supernatant;n) repeating steps l) and m) with diminishing amounts of suitable solvent as necessary to attain desired enrichment level; ando) recovering desired product;p) providing that:i) steps a) through i) are conducted at temperatures greater than about -25.degree. C. and solvent used is not dichloromethane or other halogenated solvent, andii) steps j) through n) are conducted at temperatures greater than about -20.degree. C.