Process for the preparation of metallocene compounds

Details Process for the preparation of metallocene compounds Process for the preparation of metallocene compounds

1999-09-13

2001-02-20

Nazario-Gonzalez, Porfirio (Department: 1621)

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

Organic compounds

Heavy metal containing

C556S001000, C556S012000, C556S022000, C556S043000, C556S053000, C556S058000, C534S011000, C534S015000, C526S160000, C526S943000, C502S103000, C502S117000

Reexamination Certificate

active

06191294

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a new process, particularly simple, convenient and practical, for the preparation of metallocene compounds; more specifically, it relates to a process for the direct synthesis of metallocenes wherein the transition metal atom has at least one sigma ligand selected from the group consisting of linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl and C
7
-C
20
arylalkyl radicals, optionally containing Si or Ge atoms. These metallocenes are useful as catalyst components, e.g. in the polymerization, oligomerization and hydrogenation of olefins, in association with alumoxanes and/or compounds able to form alkylmetallocene cations.
PRIOR ART DISCLOSURE
Homogeneous catalytic systems based on metallocenes in association with an aluminum alkyl compound or an alumoxane are well known in the state of the art and are widely used in the polymerization reaction of olefins. For instance, the European Patent Application EP 0 129 368 discloses catalysts comprising mono, di and tricyclopentadienyl coordination complexes with a transition metal and an alumoxane; more specifically, said coordination complexes are metallocene compounds of general formula:
(C
5
R′
m
)
p
R″
s
(C
5
R′
m
)MQ
3-p
wherein (C
5
R′
m
) is an optionally substituted cyclopentadienyl group, in which ′to can be hydrogen, an alkyl, alkenyl, aryl, alkylaryl or arylalkyl radical, having from 1 to 20 carbon atoms, or two or four substituents R′ on the same cyclopentadienyl group can form one or two rings, having 4 to 6 carbon atoms; R″ is a divalent radical bridging the two cyclopentadienyl groups; M is a transition metal belonging to groups 4, 5 or 6 of the Periodic Table of the Elements; p is 0, 1 or 2; s is 0 or 1; m is 0 to 5; and the sigma ligands Q, same or different from each other, can be halogen atoms, alkyl, cycloalkyl, alkenyl, aryl, alkylaryl or arylalkyl radicals.
In metallocenes known in the state of the art, the sigma ligands of the central metal atom are usually halogen, preferably chlorine; also metallocene dialkyls, particularly dimethyls, have been developed and are widely used as catalyst components for olefin polymerization reactions, in association with suitable cocatalysts, such as alumoxanes and borate salts, e.g. [Ph
3
C]
+
[B(C
6
F
5
)
4
]
−
or [HN(n-Bu)
3
]
+
[B(C
6
F
5
)
4
]
−
. When the sigma ligands of the central metal atom are alkyl or aryl groups, the above metallocenes are usually obtained according to a process comprising the following steps:
1) preparing the metallocene dihalide, usually the metallocene dichloride, by reacting suitable ligand/s with MX
4
, wherein X is halogen (usually TiCl
4
or ZrCl
4
);
2) converting the metallocene dihalide obtained in step (1) into the corresponding dialkyl or diaryl complex, by substitution of the halogens linked to the metal atom with the desired alkyl or aryl groups, by means of an alkylating agent such as alkyllithium, dialkylmagnesium or the corresponding Grignard reagent.
Nevertheless, the above metallocenes can not be expediently synthesized by the existing methodology; in fact, prior art processes imply always the synthesis of the metallocene dihalide, that is subsequently transformed into the target product, thus leading to unsatisfactory total yields and requiring at least two process steps.
E. Samuel et al. (
J. Organomet. Chem.,
113(4):331-339, 1976) describe the preparation of bis-fluorenyl zirconium dimethyl by treating ZrCl
4
with lithium fluorenyl (obtained by reacting fluorenyl and MeLi) in THF at 13 78° C., and subsequently treating the thus obtained bis-fluorenyl zirconium dichloride with MeLi. This process has the disadvantage of giving a final crude product in low total yields and it requires two reaction steps.
Even in the case of bridged metallocenes, low reaction yields are obtained. For instance, F. Wild et al. (
J. Organomet. Chem.,
288:63-67, 1985) describe the synthesis of chiral ansa-zirconocene derivatives with ethylene-bridged ligands; in particular, it is reported the preparation of ethylenebis(1-indenyl) zirconium dichloride by reaction of the dilithium salt of bis(1-indenyl)ethane with ZrCl
4
, in a yield of about 35%. Better results have been obtained by I. M. Lee et al. (
Organometallics,
11:2115-2122, 1992), who prepared ethylenebis(1-indenyl) zirconium dichloride in a yield of 52%.
Furthermore, M. Bochmann and S. J. Lancaster (
Organometallics,
12(3):633-640, 1993) report a process for the synthesis of several chiral methyl zirconocene and hafnocene complexes, and in particular the conversion of ethylenebis(1-indenyl) zirconium dichloride to the corresponding dimethyl derivative, in a yield of 21%. Better results were obtained by S. Rodewald and R. F. Jordan, who prepared ethylenebis(1-indenyl) zirconium dimethyl by reaction of the corresponding dichloride with Me
2
Mg in Et
2
O followed by work up with dioxane, with a yield of 90% (
J. Am. Chem. Soc.,
116:4491-4492, 1994).
Therefore, according to the literature procedures, ethylenebis(1-indenyl) zirconium dimethyl can be obtained at best in two reaction steps, in an unsatisfactory total yield lower than 50% (52·90/100=46.8%).
The International Patent Application WO 96/19488 describes a method for preparing metallocene alkyls comprising, among the others, the steps of reacting a cyclopentadienyl ligand metal salt with a perhalogenated group 4-6 transition metal compound and subsequently reacting the thus obtained metallocene dihalide with at least two molar equivalents of an alkylating agent; after separation and purification procedures, metallocene alkyls are isolated.
Even in this case, two separate reaction steps are required, as well as the intermediate isolation of the dihalide metallocene, thus lowering notably the final yields and rendering the whole process more laborious and time consuming.
Therefore, the prior art processes for producing metallocene derivatives having hydrocarbon sigma ligands are inadequate for a commercially viable and practical production of said derivatives, for use as catalyst components for olefin polymerization; it is felt the need for a simpler and more convenient and practical method to produce the above metallocene derivatives in satisfactory yields.
SUMMARY OF THE INVENTION
The Applicant has now unexpectedly found a new process for the preparation of cyclopentadienyl metallocene compounds of formula (I):
(Cp)(ZR
1
m
)
n
(A)
r
ML
p
L′
q
  (I)
wherein (ZR
1
m
)
n
is a divalent group bridging Cp and A, Z being C, Si, Ge, N or P, and the R
1
groups, equal or different from each other, being hydrogen or linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl or C
7
-C
20
arylalkyl groups;
Cp is a substituted or unsubstituted cyclopentadienyl group, optionally condensed to one or more substituted or unsubstituted, saturated, unsaturated or aromatic rings, containing from 4 to 6 carbon atoms, optionally containing one or more heteroatoms;
A is —O—, —S—, —N(R
2
)—, wherein R
2
is hydrogen, a linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl or C
7
-C
20
arylalkyl, or A has the same meaning of Cp;
M is a transition metal belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups of the Periodic Table of the Elements (IUPAC version);
the substituents L, same or different from each other, are monoanionic sigma ligands selected from the group consisting of linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl and C
7
-C
20
arylalkyl groups, optionally containing one or more Si or Ge atoms; preferably, the substituents L are the same;
the substituents L′, same or different from each other, are halogens or —OR
5
, wherein R
5
has the same meaning of R
1

Affiliated with

Also associated with

Rating

Process for the preparation of metallocene compounds does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for the preparation of metallocene compounds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of metallocene compounds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2608435