Method for producing metallocenes

Details Method for producing metallocenes Method for producing metallocenes

2000-01-27

2002-04-02

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C556S012000, C556S001000, C556S053000, C556S058000, C502S103000, C502S117000, C502S120000, C526S160000, C526S943000

Reexamination Certificate

active

06365763

ABSTRACT:

The present invention relates to a process for preparing rac/meso-metallocenes, the rac/meso-metallocenes themselves and the use of the rac/meso-metallocenes for preparing polyolefins.
Racemic metallocenes containing aromatic, partially hydrogenated or hydrogenated &pgr; ligands have been described as catalyst precursors for the polymerization of olefins, for example in J. Organomet. Chem. 497(1995)181, Angew. Chem. 104 (1992) 1373, EPA 0 344 887, J. Mol. Catal. A. Chem. 102 (1995) 59, J. Am. Chem. Soc. 118 (1996) 2105, Macromolecules 27 (1994) 4477, Macromolecules 29 (1996) 2331, EPA 0 185 918, EPA 0 537 686, EP 0 485 820 or EP 0 485 821.
In the synthesis of metallocenes containing aromatic &pgr; ligands, for example indenyl ligands, great effort is made to isolate the rac-metallocene, since only this form enables, for example, isotactic polypropylene to be prepared stereo specifically. The meso form of the metallocene is separated off.
It is an object of the present invention to provide an efficient, rapid, inexpensive and yield-optimized direct synthesis of metallocenes by means of which highly isotactic polyolefins can be prepared inexpensively.
We have found that this object is achieved by a process for the direct preparation of rac/meso-metallocenes. The rac/meso-metallocenes prepared according to the present invention can, surprisingly, be used directly as catalyst component for olefin polymerization without an additional, costly and yield-reducing isolation of the rac-form being necessary.
The present invention accordingly provides a process for preparing an rac/meso-metallocene of the formula I having an rac/meso ratio of from >20:1 to <200:1.
where
M is a metal of group IIIb, IVb, Vb or VIb of the Periodic Table of the Elements and is preferably a metal of group IVb, i.e. Ti, Zr or Hf, particularly preferably Zr or Hf,
the radicals X are identical or different, preferably identical, are each a hydrogen atom, a C
1
-C
40
-group such as C
1
-C
10
-alkyl, C
1
-C
10
-alkoxy, C
6
-C
20
-aryl, C
6
-C
20
-aryloxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkenyl, C
7
-C
40
-alkylaryl or C
8
-C
40
-arylalkenyl, an OH group, a halogen atom or a pseudohalogen such as nitrile, with preference being given to linear or branched C
1
-C
10
-alkyl and halogen atoms and very particular preference being given to chlorine and methyl,
the radicals R
1
and R
2
are identical or different, with even radicals having the same index being able to be different, and are each a hydrogen atom, a C
1
-C
40
-group such as C
1
-C
10
-alkyl, C
1
-C
10
-alkoxy, C
6
-C
20
-aryl, C
6
-C
20
-aryloxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkenyl, C
7
-C
40
-alkylaryl or C
8
-C
40
-arylalkenyl, an OH group, a halogen atom or a pseudohalogen such as nitrile, or a NR
5
2
, SR
5
3
, OSiR
5
3
or SiR
5
3
or PR
5
2
group with R
5
defined as for X, with preference being given to the radicals R
2
being identical and each being a hydrogen atom and the radicals R
1
being identical and each being hydrogen or linear or branched C
1
-C
10
-alkyl,
the radicals R
3
and R
4
are identical or different, with even radicals having the same index being able to be different, and are each a hydrogen atom, a C
1
-C
40
-group such as C
1
-C
10
-alkyl, C
1
-C
10
-alkoxy, C
6
-C
20
-aryl, C
6
-C
20
-aryloxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkenyl, C
7
-C
40
-alkylaryl or C
8
-C
40
-arylalkenyl, an OH group, a halogen atom or a pseudohalogen such as nitrile, or an NR
5
2
, SR
5
, OSiR
5
3
or SiR
5
3
or PR
5
2
group with R
5
as defined for X, or the radicals R
3
and R
4
together form an unsubstituted butadienyl group, with particular preference being given to the radicals R
3
and R
4
being hydrogen, linear or branched C
1
-C
10
-alkyl or together forming an unsubstituted butadienyl group,
B is a bridge between the indenyl ligands which may be, for example, from single- to four-membered, with preference being given to single- and two-membered bridges, with the proviso that the radicals R
1
, R
2
, R
3
and R
4
are not all identical and that, if R
3
and R
4
together form an unsubstituted butadienyl group, R
1
and R
2
are hydrogen, comprising the steps:
a) reaction of a substituted cyclopentadiene of the formula A
 with a bridging reagent BY
2
to form a bridged biscyclopentadienyl ligand system,
b) reaction of the bridged biscyclopentadienyl ligand system with a metal halide to form a metallocene of the formula Ia,
c) and, if desired, reaction of a metallocene of the formula Ia with an organometallic compound R
3
M
1
to form a metallocene of the formula Ib,
where all steps are carried out in the same solvent or solvent mixture.
The invention further provides chiral rac/meso-metallocenes of the formula I having an rac/meso ratio of from >20:1 to <200:1
where
M is a metal of group IIIb, IVb, Vb or VIb of the Periodic Table of the Elements and is preferably a metal of group IVb, i.e. Ti, Zr or Hf, particularly preferably Zr or Hf,
the radicals X are identical or different, preferably identical, and are each a hydrogen atom, a C
1
-C
40
-group such as C
1
-C
10
-alkyl, C
1
-C
10
-alkoxy, C
6
-C
20
-aryl, C
6
-C
20
-aryloxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkenyl, C
7
-C
40
-alkylaryl or C
8
-C
40
-arylalkenyl, an OH group, a halogen atom or a pseudohalogen such as nitrile, with preference being given to linear or branched C
1
-C
10
-alkyl and halogen atoms and very particular preference being given to chlorine and methyl,
the radicals R
1
and R
2
are identical or different, with even radicals having the same index being able to be different, and are each a hydrogen atom, a C
1
-C
40
-group such as C
1
-C
10
-alkyl, C
1
-C
10
-alkoxy, C
6
-C
20
-aryl, C
6
-C
20
-aryloxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkenyl, C
7
-C
40
-alkylaryl or C
8
-C
40
-arylalkenyl, an OH group, a halogen atom or a pseudohalogen such as nitrile, or an NR
5
2
, SR
5
, OSiR
5
3
, SiR
5
3
or PR
5
2
group where R
5
is defined as for X, with preference being given to the radicals R
2
being identical and each being a hydrogen atom and the radicals R
1
being identical and being hydrogen or linear or branched C
1
-C
10
-alkyl,
the radicals R
3
and R
4
are identical or different, with even radicals having the same index being able to be different, and are each a hydrogen atom, a C
l
-C
40
-group such as C
1
-C
10
-alkyl, C
1
-C
10
-alkoxy, C
6
-C
20
-aryl, C
6
-C
20
-aryloxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkenyl, C
7
-C
40
-alkylaryl or C
8
-C
40
-arylalkenyl, an OH group, a halogen atom or a pseudohalogen such as nitrile, or an NR
5
2
, SR
5
, OSiR
5
3
, SiR
5
3
or PR
5
2
group where R
5
is as defined for X, or the radicals R
3
and R
4
together form an unsubstituted butadienyl group, with particular preference being given to the radicals R
3
and R
4
being hydrogen, linear or branched C
1
-C
10
-alkyl or together forming an unsubstituted butadienyl group,
B is a bridge between the indenyl ligands which can, for example, be from single- to four-membered, with preference being given to single- and two-membered bridges, with the proviso that the radicals R
1
, R
2
, R
3
and R
4
are not all identical and that, if R
3
and R
4
together form an unsubstituted butadienyl group, R
1
and R
2
are hydrogen.
The invention also provides a catalyst comprising a) at least one chiral rac/meso-metallocene of the formula I and b) at least one cocatalyst, a process for the polymerization of olefins in the presence of this catalyst and also provides for the use of this catalyst for olefin polymerization.
In the process of the present invention, the ligand system is prepared first and then, without isolating the bridged biscyclopentadienyl ligand system, the rac/meso-metallocene of the formula Ia is prepared and can be reacted further to give a rac/meso-metallocene of the formula Ib.
As illustrated in Scheme 1, the process starts with the preparation of a bridged biscyclopentadienyl system from a substituted cyclopentadiene of the formula A, preferably an alkyl-substituted cyclopentadiene, by deprotonation using a strong

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