Metallocenes and process for the preparation of metallocenes

Details Metallocenes and process for the preparation of metallocenes Metallocenes and process for the preparation of metallocenes

2000-04-06

2001-01-16

Nazario-Gonzalez, Porfirio (Department: 1621)

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

Organic compounds

Heavy metal containing

C556S054000, C502S103000, C502S117000, C526S160000, C526S352000, C526S943000

Reexamination Certificate

active

06175026

ABSTRACT:

TECHNICAL FIELD
The present invention relates to metallocenes useful as catalyst in the polymerization of olefins and to a process for the preparation of metallocenes.
BACKGROUND OF THE INVENTION
Metallocenes for the polymerization of olefins have been known for several years. European Patent Application EP 0416815 discloses constrained geometry metal complexes comprising a single cyclopentadienyl group and at least an heteroatom Y chosen from —O—, —S—, —NR—, —PR—.
These metallocenes have been synthesized by contacting a tetravalent metal reactant and a group 1 derivative or Grignard derivative of the cyclopentadienyl compound.
Methods for the preparation of metallocenes for the polymerization of olefins generally involve some variant of the reaction of a substituted cyclopentadienylalkali-metal salt with a transition metal halide in the proper molar ratio to produce the desired number of ligands to the transition metal. For instance, the U.S. Pat. No. 5,158,920 describes the preparation of isopropylidene (cyclopentadienyl-9-fluorenyl) zirconium dimethyl by deprotonation of fluorene (using methyllithium as deprotonating agent) to obtain the ionic species fluorenyl lithium, followed first by the ligand forming reaction with 6,6 dimethylfulvene, and then by the reaction with zirconium tetrachloride to form the metallocene.
These known methods are carried out under particular conditions incompatible with usual polymerization conditions. Consequently, the known methods,cannot be carried out “in situ” in the polymerization reactor but have to be carried out separately. In most cases the metallocenes obtained by these known methods have to be separated from the reaction mixture and stored under special conditions. Additionally, the known methods do not present a high productivity and a high selectivity.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the aforementioned problems by providing a novel process for the preparation of metallocenes presenting a high productivity and a high selectivity and which can be carried out “in situ”. Another object of the present invention is to provide a process permitting the preparation of new metallocenes. Still another object of the invention is to provide novel metallocenes. A further object is to provide for the use of the said novel metallocenes in the polymerization of olefins.
The invention is thus related to metallocenes corresponding to the formula (I)
wherein M is a group 4 transition metal
each Y is selected, independently, from the group of halogen, hydrocarbyl and hydrocarbyloxy,
R
1
, R
4
are, independently, selected from the group of hydrogen, hydrocarbyl, hydrocarbyloxy,
R
2
, R
3
, R
5
, R
6
, R
7
, R
8
are, independently, selected from the group of hydrogen, hydrocarbyl, hydrocarbyloxy, with the provision that, respectively, R
2
and R
3
, R
5
and R
6
, R
7
and R
8
can be linked to each other.
The invention is further related to a process for the preparation of metallocenes comprising the following steps:
(a) contacting, in a solvent, a transition metal halide of formula MX
4
, wherein M is a group 4 transition metal and X is a halogen, with an organometallic compound of formula M′R
m
, wherein M′ is an element chosen from the groups 1, 2 and 13 of the periodic table, R is hydrogen, an alkyl, aryl, alkenyl or alkynyl group containing up to 20 carbon atoms, m=1 when M′ is a group 1 element, m=2 when M′ is a group 2 element, m=3 when M′ is a group 13 element, in order to reduce M, which leads to a subvalent transition metal halide of formula MX
2
,
(b) purifying the transition metal halide MX
2
obtained in (a) in order to eliminate the products of formula M′X
m
formed during the step (a),
(c) contacting the purified subvalent transition metal halide of formula MX
2
obtained in (b) with at least one fulvene compound in order to obtain a metallocene.
DETAILED DESCRIPTION
All references to the Periodic Table of Elements herein refer to the version published in CRC Handbook of Chemistry and Physics, 77th Edition, 1996/97; the notation used being the new IUPAC notation of groups.
According to a first aspect, the present invention relates to novel metallocenes corresponding to formula (I) wherein M is a group 4 transition metal, each Y is selected, independently, from the group of halogen, hydrocarbyl and hydrocarbyloxy, R
1
, R
4
are, independently, selected from the group of hydrogen, hydrocarbyl, hydrocarbyloxy, and R
2
, R
3
, R
5
, R
6
, R
7
, R
8
are, independently, selected from the group of hydrogen, hydrocarbyl, hydrocarbyloxy, with the provision that, respectively, R
2
and R
3
, R
5
and R
6
, R
7
and R
8
can be linked to each other. By hydrocarbyl are designated those groups containing hydrogen and carbon atoms, such as alkyl, aryl, alkenyl, allyl, alkynyl, cycloalkyl groups; by hydrocarbyloxy are designated those groups containing hydrogen, carbon and oxygen atoms, such as alkoxy or acetyl groups.
Suitable hydrocarbyl and hydrocarbyloxy groups will contain from 1 to 20 carbon atoms. Preferably, R
1
, R
4
, R
2
, R
3
, R
5
, R
6
, R
7
, R
8
are selected from the group of hydrogen and hydrocarbyl. Preferred hydrocarbyl groups are those containing from 1 to 12 carbon atoms and include straight and branched alkyl, alkenyl, allyl and alkynyl radicals, cyclic hydrocarbon radicals, alkyl-substituted cyclic hydrocarbon radicals, aromatic radicals and alkyl substituted aromatic radicals. Moreover, groups R
2
and R
3
, groups R
5
and R
6
, groups R
7
and R
8
, respectively, can be linked to each other forming a fused ring system which may be fully or partially saturated or unsaturated. For example groups R
2
and R
3
, groups R
5
and R
6
, groups R
7
and R
8
, respectively, can jointly be a divalent polyalkylene group —(CH
2
)
n
—where n is a number from 1 to 20 or a divalent polyvinylene group —(CH═CH)
n
—.
In the metallocenes according to the invention, each Y is, independently, selected from the group of halogen, hydrocarbyl and hydrocarbyloxy. Suitable hydrocarbyl and hydrocarbyloxy groups will contain from 1 to 20 carbon atoms, preferably from 1 to 10 carbon atoms. Y is preferably a halogen, and more specifically chlorine. Especially preferred are metallocenes where the two Y groups are identical.
In the metallocenes according to the invention, the transition metal M is preferably chosen from titanium and zirconium.
Good results have been obtained with metallocenes wherein R
4
, R
5
, R
6
, R
7
and R
8
are hydrogen atoms and R
1
, R
2
and R
3
are selected from hydrogen and hydrocarbyl, with the provision that R
2
and R
3
can be linked together. Preferred metallocenes are those wherein R
4
, R
2
, R
3
, R
5
, R
6
, R
7
, R
8
are hydrogen atoms and wherein R
1
is a hydrocarbyl radical, more preferably an aromatic radical. Especially preferred is a metallocene wherein M is Ti or Zr, Y is a halogen atom, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
and R
8
are hydrogen atoms and R
1
is a phenyl group.
According to a second aspect, the present invention relates to a process for the preparation of metallocenes comprising the following steps:
(a) contacting, in a solvent, a transition metal halide of formula MX
4
, wherein M is a group 4 transition metal and X is a halogen, with an organometallic compound of formula M′R
m
, wherein M′ is an element chosen from the groups 1, 2 and 13 of the periodic table, R is hydrogen, an alkyl, aryl, alkenyl or alkynyl group containing up to 20 carbon atoms, m=1 when M′ is a group 1 element, m=2 when M′ is a group 2 element, m=3 when M′ is a group 13 element, in order to reduce M, which leads to a subvalent transition metal halide of formula MX
2
,
(b) purifying the transition metal halide MX
2
obtained in (a) in order to eliminate the products of formula M′X
m
formed during the step (a),
(c) contacting the purified subvalent transition metal halide of formula MX
2
obtained in (b) with at least one fulvene compound in order to obtain

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