Method for producing monoaryloxy-ansa-metallocenes

Details Method for producing monoaryloxy-ansa-metallocenes Method for producing monoaryloxy-ansa-metallocenes

2001-05-17

2003-09-16

Nazario-Gonzalez, Porfirio (Department: 1621)

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

Organic compounds

Heavy metal containing

C556S012000, C556S043000, C556S053000, C526S127000, C526S160000, C526S943000, C502S103000, C502S117000

Reexamination Certificate

active

06620953

ABSTRACT:

The present invention relates to a stereoselective process for preparing monoaryloxy-ansa-metallocenes and to their use in the polymerization of olefins.
Metallocenes can, possibly in combination with one or more cocatalysts, be used as catalyst components for the polymerization and copolymerization of olefins. In particular, halogen-containing metallocenes are used as catalyst precursors which can, for example, be converted into a polymerization-active cationic metallocene complex by means of an aluminoxane(EP-A-129368).
Metallocenes are of great interest not only for the polymerization of olefins, but they can also be used as hydrogenation, epoxidation, isomerization and C—C coupling catalysts (Chem. Rev., 92 (1992), 965-994).
The preparation of metallocenes is known per se (U.S. Pat. No. 4,752,597; U.S. Pat. No. 5,017,714; EP-A-320762; EP-A-416815; EP-A-537686; EP-A-669340; H. H. Brintzinger et al., Angew. Chem., 107 (1995), 1255; H. H. Brintzinger et al., J. Organomet. Chem. 232 (1982), 233). For this purpose, for example, cyclopentadienyl-metal compounds can be reacted with halides of transition metals such as titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, cerium and thorium.
It is also known from the literature that metallocenes can be obtained, for example, by reaction of cyclopentadienes with amides of elements of group 4 of the Periodic Table of the Elements (U.S. Pat. No. 5,597,935; R. F. Jordan et al., Organometallics, 15 (1996), 4030).
For the preparation of isotactic polypropylene (i-PP), use is generally made of ansa-metallocene halides in their racemic form. Substituted racemic ansa-bisindenylzirconium dichlorides have been found to give particularly good results and are therefore industrially important (EP 0485823, EP 0549900, EP 0576970, WO 98/40331). These industrially interesting metallocene dichlorides are predominantly sparingly soluble compounds, which makes, for example, the purification of these racemic metallocenes by recrystallization very difficult.
In their preparation, the desired substituted racemic ansa-bisindenyl-metallocene dichlorides are generally obtained together with the meso forms as 1:1 rac/meso diastereomer mixtures, as a result of which the yields of the desired rac-metallocenes based on the valuable ligand starting compounds are greatly restricted. The crude products formed in the preparation further comprise, in addition to the diastereomer mixtures, additional inorganic by-products (e.g. salts) and organic by-products (e.g. unreacted substituted cyclopentadienyl ligands). When metallocenes are used as catalyst components, in both homogeneous and heterogeneous catalyst systems, the by-products, in particular the meso form of the metallocene, adversely affect the catalyst activity in olefin polymerization and the specification of the polymer (for example, excessively high contents of extractables in the i-PP). Various methods are known for separating off the various by-products (U.S. Pat. No. 5,455,366, EP-A-0576970, DE-A-19547247, DE-A-19547248, U.S. Pat. No. 5,556,997).
Dormond et al., J. Organomet. Chem., vol. 101 (1), (1975) pp. 71-84 described chiral, phenoxy-substituted ansa-titanocenes.
Owing to the above-described rac/meso problems and the complicated purification, the costs of preparing the ansa-metallocene catalyst component are not yet in a desirable range.
It is an object of the present invention to find a more economical process for preparing readily purifiable racemic metallocenes, which is suitable, in particular, for preparing racemic, substituted ansa-bisindenyl-metallocenes which can be used directly as catalyst components in the polymerization of propylene.
We have found that this object is achieved by the use of specific transition metal compounds of the formula (I) for preparing metallocenes of the formula (II).
The present invention accordingly provides a process for preparing readily soluble and easily purifiable monoaryloxy-metallocenes of the formula (II), which comprises reacting a ligand starting compound (III) with a transition metal compound of the formula (I),
where
M is a metal of transition group III, IV, V or VI of the Periodic Table of the Elements, in particular Ti, Zr or Hf, particularly preferably zirconium,
X is a halogen atom, in particular chlorine,
Ar is a C
6
-C
40
aromatic group, preferably C
6
-C
24
-aryl, C
5
-C
24
-heteroaryl such as pyridyl, furyl or quinolyl, C
7
-C
30
-alkylaryl, fluorinated C
6
-C
24
-aryl or fluorinated C
7
-C
30
-alkylaryl, particularly preferably a C
6
-C
14
-aryl group substituted by C
1
-C
6
-alkyl and/or C
6
-C
10
-Aryl radicals,
D is an uncharged Lewis base ligand, preferably a linear, cyclic or branched oxygen-, sulfur-, nitrogen- or phosphorus-containing hydrocarbon, particularly preferably an ether, polyether, amine or polyamine,
M
2
is Li, Na, K, MgCl, MgBr, Mg or Ca,
R
1
are identical or different and are each Si(R
12
)
3
, where R
12
are identical or different and are each a hydrogen atom or a C
1
-C
40
group, preferably C
1
-C
20
-alkyl, C
1
-C
10
-fluoroalkyl, C
1
-C
10
-alkoxy, C
6
-C
20
-aryl, C
6
-C
10
-fluoroaryl, C
6
-C
10
-aryloxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkyl, C
7
-C
40
-alkylaryl or C
8
-C
40
-arylalkenyl,
or R
1
is a C
1
-C
30
group, preferably C
1
-C
25
-alkyl such as methyl, ethyl, tert-butyl, cyclohexyl or octyl, C
2
-C
25
-alkenyl, C
3
-C
15
-alkylalkenyl, C
6
-C
24
-aryl, C
5
-C
24
-heteroaryl, C
7
-C
30
-arylalkyl, C
7
-C
30
-alkylaryl, fluorinated C
1
-C
25
-alkyl, fluorinated C
6
-C
24
-aryl, fluorinated C
7
-C
30
-arylalkyl or fluorinated C
7
-C
30
-alkylaryl,
or two or more radicals R
1
are joined to one another so that the radicals R
1
and the atoms of the cyclopentadienyl ring which connect them form a C
4
-C
24
ring system which may be substituted,
R
2
are identical or different and are each Si(R
12
)
3
, where R
12
are identical or different and are each a hydrogen atom or a C
1
-C
40
group, preferably C
1
-C
20
-alkyl, C
1
-C
10
-fluoroalkyl, C
1
-C
10
-alkoxy, C
6
-C
14
-aryl, C
6
-C
10
-fluoroaryl, C
6
-C
10
-aryloxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkyl, C
7
-C
40
-alkylaryl or C
8
-C
40
-arylalkenyl,
or R
2
is a C
1
-C
30
group, preferably C
1
-C
25
-alkyl such as methyl, ethyl, tert-butyl, cyclohexyl or octyl, C
2
-C
25
-alkenyl, C
3
-C
15
-alkylalkenyl, C
6
-C
24
-aryl, C
5
-C
24
-heteroaryl, C
7
-C
30
-arylalkyl, C
7
-C
30
-alkylaryl, fluorinated C
1
-C
25
-alkyl, fluorinated C
6
-C
24
-aryl, fluorinated C
7
-C
30
-arylalkyl or fluorinated C
7
-C
30
-alkylaryl,
or two or more radicals R
2
are joined to one another so that the radicals R
2
and the atoms of the cyclopentadienyl ring which connect them form a C
4
-C
24
ring system which may in turn be substituted,
x is equal to the oxidation number of M minus 1,
n is from 1 to 5 when k=0, and n is from 0 to 4 when k=1,
n′ is from 1 to 5 when k=0, and n, is from 0 to 4 when k=1,
k is zero or 1 and, where the metallocene is unbridged when k=0 and the metallocene is bridged when k=1, with preference being given to k=1, and
p is 1 for doubly positively charged metal ions or 2 for singly positively charged metal ions or metal ion fragments,
y is from 0 to 2,
B is a bridging structural element between the two cyclopentadienyl rings.
Examples of B are M
3
R
13
R
14
groups, where M
3
is carbon, silicon, germanium or tin and R
13
and R
14
are identical or different and are each a C
1
-C
20
-hydrocarbon-containing group such as C
1
-C
10
-alkyl, C
6
-C
14
-aryl or trimethylsilyl. B is preferably CH
2
, CH
2
CH
2
, CH(CH
3
)CH
2
, CH(C
4
H
9
)C(CH
3
)
2
, C(CH
3
)
2
, (CH
3
)
2
Si, (CH
3
)
2
Ge, (CH
3
)
2
Sn, (C
6
H
5
)
2
Si, (C
6
H
5
)(CH
3
)Si, Si(CH
3
)(SiR
20
R
21
R
22
), (C
6
H
5
)
2
Ge, (C
6
H
5
)
2
Sn, (CH
2
)
4
Si, CH
2
Si(CH
3
)
2
, o-C
6
H
4
or 2,2′-(C
6
H
4
)
2
, where R
20
, R
21
, R
22
are identical or different and are each a C
1
-C
20
-hydrocarbon-containing group such as C
1
-C
10
-alkyl or C
6
-C
14
-aryl. It is also possible for B toge

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