Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
2000-01-11
2001-11-20
Wu, David W. (Department: 1713)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S104000, C502S117000, C526S160000, C526S943000, C526S075000, C556S053000
Reexamination Certificate
active
06319874
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 as catalyst components for preparing isotactic polyolefins.
Racemic metallocenes (rac-metallocenes) containing partially hydrogenated or hydrogenated p 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, Organometallics 12 (1993) 4391 or Chem. Ber. 127 (1994) 2417, J. Am. Chem. Soc. 118 (1996) 2105, Macromolecules 27 (1994) 4477 or Macromolecules 29 (1996) 2331, EPA 0 344 887, J. Mol. Catal. A. Chem. 102 (1995) 59, EPA 0 185 918, EPA 0 537 686, EP 0 485 820 or EP 0 485 821.
In the synthesis of metallocenes, great effort is made to isolate the racemic form of the metallocene, since only this form enables, for example, isotactic polypropylene to be prepared stereospecifically. The meso form of the metallocene is separated off. In the preparation of metallocenes containing partially hydrogenated or hydrogenated p ligands, the racemic form of the unhydrogenated metallocene is isolated first and then hydrogenated. Thus, for example, rac-dimethylsilanediylbis-(4,5,6,7-tetrahydroindenyl)zirconium dichloride can be prepared from rac-dimethylsilanediylbisindenylzirconium dichloride by hydrogenation of the octahydro derivative. Such and similar reactions are described, for example, in EPA 0 344 887, J. Organomet. Chem. 497 (1995) 181, Organometallics 10 (1991) 1501 or J. Organomet. Chem. 342 (1988) 21.
The known synthetic procedures for hydrogenating the aromatic ligand skeleton of rac-metallocenes all in principle follow the same route. The purified rac-metallocene is dissolved or suspended in dichloromethane and hydrogenated under a high hydrogen pressure in the presence of platinum black or platinum dioxide (cf. J. Organomet. Chem. 342 (1988) 21 or EPA 0 344 887).
Dichloromethane and other chlorinated solvents can only be used in relatively large amounts with observance of strict occupational hygiene measures and environmental regulations. Only low-activity hydrogenation catalysts such as platinum black or platinum dioxide can be used in chlorinated solvents so as to avoid dehalogenation reactions. The dehalogenation reactions lead to decomposition of the product and to corrosion problems.
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 containing tetrahydroindenyl ligands. 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
1
and X
2
(in the following also collectively referred to as 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
1a
and R
1b
(in the following also collectively referred to as R
1
), and R
2a
and R
2b
(in the following also collectively referred to as R
2
), are identical or 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
, OSiR
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,
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,
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) hydrogenation of the metallocene of the formula Ia to form a metallocene of the formula Ib
d) and, if desired, reaction of a metallocene of the formula Ib with an organometallic compound R
3
M
1
to form a metallocene of the formula Ic,
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
1
and X
2
(in the following also collectively referred to as X) are identical or 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, 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
1a
and R
1b
(in the following also collectively referred to as R
1
), and R
2a
and R
2b
(in the following also collectively referred to as R
2
) are identical or 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
, OSiR
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,
B is a bridge between the tetrahydroindenyl ligands which can, for example, be from single- to four-membered, with preference being given to single- and two-membered bridges.
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 and also provides for the use of the catalyst for the polymerization of olefins or in a process for the polymerization of olefins.
In the process of the present invention, the ligand system is prepared first and, without isolating the bridged bisindenyl ligand system, the rac/meso-metallocene of the formula Ia is then prepared and subsequently hydrogenated to form the bistetrahydroindenyl metallocene of the formula Ib. The rac/meso-metallocene of the formula Ib can be reacted further to give the rac/meso-metallocene of the formula Ic.
As illustrated in Scheme 1, the process starts with the preparation of a bridged bisindenyl system from an indene of the formula A by deprotonation using a strong base such as butyllithium or potassium hydride in a suitable solvent or so
Bingel Carsten
Fraaije Volker
Kueber Frank
Winter Andreas
Basell Polyolefine GmbH
Harlan R.
Keil & Weinkauf
Wu David W.
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