Process for preparing a methylene-bridged...

Details Process for preparing a methylene-bridged... Process for preparing a methylene-bridged...

1999-06-23

2001-07-03

Nazario-Gonzalez, Porfirio (Department: 1621)

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

Organic compounds

Heavy metal containing

C556S001000, C556S053000, C556S058000, C534S015000, C502S103000, C502S117000, C526S160000, C526S943000, C987S002000

Reexamination Certificate

active

06255508

ABSTRACT:

The present invention relates to a process for preparing a methylene-bridged biscyclopentadienyl compound and the use of this process as a substep in the preparation of a methylene-bridged biscyclopentadienyl metallocene which can be used as a catalyst component, e.g. for the preparation of polyolefins.
The preparation of polyolefins in the presence of metailocenes in combination with aluminoxanes or other cocatalysts which, owing to their Lewis acidity, can convert the neutral metallocene into a cation and stabilize it is known from the literature.
Metallocenes and semi-sandwich complexes are Qf great interest not only in connection with the polymerization or oligomerization of olefins, but they can also be used as hydrogenation, epoxidation, isomerization and C—C coupling catalysts (Chem. Rev. 1992, 92, 965-994).
U.S. Pat. No. 4,892,851 and EP-A461 566 disclose carbon-bridged metallocenes. The synthesis of methylene-bridged metallocenes proceeds via the preparation of the methylene-bridged biscyclopentadienyl ligand system which has to be carried out in a plurality of stages and proceeds with only very low yields, cf. J. Am. Chem. Soc. 106, 1984, 7451 and Helv. Chim. Acta 48, 1965, 955.
It is also known from the literature that cyclopentadiene can be reacted directly with cyclic ketones with addition of a base to give bridged biscyclopentadienyl ligands, cf. J. Chem. Research (S), 1992, 162. This synthesis proceeds with low yields and requires a complicated subsequent chromatographic purification.
It is an object of the present invention to provide a simple and economical process for preparing methylene-bridged biscyclopentadienyl compounds in high yields.
The object of the present invention is achieved by a process for preparing a methylene-bridged biscyclopentadienyl compound, which comprises reacting one or two cyclopentadienyl compounds LH with formaldehyde in monomeric, oligomeric or polymeric form or with formaldehyde-generating reagents in the presence of at least one base and at least one phase transfer catalyst.
The methylene-bridged biscyclopentadienyl compound has the formula I
where L are, independently of one another, identical or different and are each a cyclopentadienyl group.
The cyclopentadienyl groups L in formula I can be unsubstituted or substituted by, for example, C
1
-C
20
-radicals R such as C
1
-C
20
-alkyl, C
6
-C
20
-aryl, C
6
-C
20
-alkylaryl, C
7
-C
20
-arylalkyl or C
2
-C
20
-alkenyl. The radicals R can also form a ring system. The cyclopentadienyl groups L are identical or different, preferably identical.
Examples of substituted cyclopentadienyl groups L are:
tetramethylcyclopentadienyl, 3-methylcyclopentadienyl, 3-tert-butylcyclopentadienyl, methyl-tert-butylcyclopentadienyl, isopropylcyclopentadienyl, dimethylcyctopentadienyl, trimethylcyclopentadienyl, trimethylsilylcyclopentadienyl, trimethylethylcyclopentadienyl, 3-phenylcyclopentadienyl, diphenylcyclopentadienyl, indenyl, 2-methylindenyl, 2-ethylindenyl, 3-methylindenyl, 3-tert-butylindenyl, 3-trimethylsilylindenyl, 2-methyl-4-phenylindenyl, 2-ethyl-4-phenylindenyl, 2-methyl-4-naphthylindenyl, 2-methyl-4-isopropylindenyl, benzoindenyl, 2-methyl-4,5-benzoindenyl, 2-methyl-&agr;-acenaphthindenyl, 2-methyl-4,6-diisopropylindenyl, fluorenyl, 2-methylfluorenyl or 2,7-di-tert-butylfluorenyl.
Preferably, one or both cyclopentadienyl groups L are a substituted cyclopentadienyl group, in particular an indenyl derivative such as indenyl, 2-methylindenyl, 2-ethylindenyl, 3-methylindenyl, 3-tert-butylindenyl, 3-trimethylsilylindenyl, 2-methyl-4-phenylindenyl, 2-ethyl-4-phenylindenyl, 2-methyl-4-naphthylindenyl, 2-methyl-4-isopropylindenyl, benzoindenyl, 2-methyl-4,5-benzoindenyl, 2-methyl-&agr;-acenaphthindenyl or 2-methyl-4,6-diisopropylindenyl, or a fluorenyl derivative such as fluorenyl, 2-methylfluorenyl or 2,7-di-tert-butylfluorenyl.
Examples of methylene-bridged biscyclopentadienyl compounds of the formula I are:
bisindenylmethane, bis(2-methylindenyl)methane, bis(2-methyl-4-phenylindenyl)methane, bis(2-ethyl-4-phenylindenyl)methane, bis(2-methyl-4-naphthylindenyl)methane, bis(2-methyl-4,5-benzoindenyl)methane, bis(methylcyclopentadienyl)methane, biscyclopentadienylmethane, cyclopentadienyl-fluorenyl-methane, (3-methylcyclopentadienyl)-fluorenyl-methane, indenyl-fluorenyl-methane, cyclopentadienyl-indenyl-methane, 3-tert-butylcyclopentadienyl-fluorenyl-methane.
Biscyclopentadienyl compounds of the formula I in which the two cyclopentadienyl groups L are identical are prepared using one cyclopentadienyl compound LH. To prepare biscyclopentadienyl compounds of the formula I in which the two cyclopentadienyl groups L are different, use is made of two cyclopentadienyl compounds LH which are different from one another. The cyclopentadienyl compounds LH used in the process of the invention can be unsubstituted or substituted by, for example, C
1
-C
20
-radicals R such as C
1
-C
20
-alkyl, C
6
-C
20
-aryl, C
6
-C
20
-alkylaryl, C
7
-C
20
-arylalkyl or C
2
-C
20
-alkenyl. The radicals R can also form a ring system.
Examples of substituted cyclopentadienyl compounds LH are:
tetramethylcyciopentadiene, methylcyclopentadiene, tert-butylcyclopentadiene, methyl-tert-butylcyclopentadiene, isopropylcyclopentadiene, dimethylcyclopentadiene, trimethylcyclopentadiene, trimethylsilylcyclopentadiene, trimethylethylcyclopentadiene, phenylcyclopentadiene, diphenylcyclopentadiene, indene, 2-methylindene, 2-ethylindene, 3-methylindene, 3-tert-butylindene, 3-trimethylsilylindene, 2-methyl-4-phenylindene, 2-ethyl-4-phenylindene, 2-methyl-4-naphthylindene, 2-methyl-4-isopropylindene, benzoindene, 2-methyl-4,5-benzoindene, 2-methyl-&agr;-acenaphthindene, 2-methyl-4,6-diisopropylindene, fluorene, 2-methylfluorene or 2,7di-tert-butylfluorene.
Preferably one or both of the cyclopentadienyl compounds LH used in the process of the invention are a substituted cyclopentadienyl compound, in particular an indene derivative such as indene, 2-methylindene, 2-ethylindene, 3-methylindene, 3-tert-butylindene, 3-trimethylsilylindene, 2-methyl-4-phenylindene, 2-ethyl-4-phenylindene, 2-methyl-4-naphthylindene, 2-methyl-4-isopropylindene, benzoindene, 2-methyl-4,5-benzoindene, 2-methyl-acenaphthylindene or 2-methyl-4,6-diisopropylindene, or a fluorenyl derivative such as fluorene, 2-methylfluorene or 2,7-di-tert-butylfluorene.
The formaldehyde compounds used in the process of the invention are preferably formaldehyde, paraformaldehyde, formalin or formaidehyde-generating reagents such as urotropin.
Bases which can be used are, for example, hydroxides of groups Ia, IIa and IIIa of the Periodic Table of the Elements, e.g. LiOH, NaOH, KOH, RbOH, Mg(OH)
2
, Ca(OH)
2
and Sr(OH)
2
Preference is given to using exactly one base, e.g. LiOH, NaOH or KOH.
Phase transfer catalysts which can be used are quaternary ammonium salts and phosphonium salts of the formula [R
3
4
Z]
+
X
−
, where R
3
are identical or different and are each a hydrogen atom or a C
1
-C
40
-group such as a C
1
-C
20
-alkyl, C
1
-C
10
-alkoxy, C
6
-C
20
-aryl, C
2
-C
12
-alkenyl-, C
7
-C
40
-arylalkyl, C7-C
40
-alkylaryl, or C
8
-C
40
-arylalkenyl group, each of which can bear radicals such as —NR
4
3
, —SR
4
2
, —SiR
4
3
or —OsiR
4
3
, where R
4
are ident or different and are each a halogen atom, a C
1
-C
10
-alkyl group or a C
6
-C
10
-aryl group, or two or more radicals R
3
together with the atoms connecting them can form a ring system which preferably contains from 4 to 40, particularly preferably from 5 to 15, carbon atoms, Z is nitrogen or phosphorus and X is a halide, hydroxide, tetrahaloborate (e.g. tetrafluoroborate), hydrogensulfate, sulfate or hexahalophosphate (e.g. hexafluorophosphate).
Examples of compounds suitable as phase transfer catalysts are:
benzyltrimethylammonium chloride,
benzyltrimethylammonium hydroxide (in particular as an aqueous 40% strength solution),
hexadecyltrimethylammonium bromide,
hexadecyltrimethylammonium chloride (in particular as an aqueous 50% strength solution),
ethylhexadecyldimethylammonium bromide,
tetraethyl

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