Catalysts containing organochromium compounds and their use...

Details Catalysts containing organochromium compounds and their use... Catalysts containing organochromium compounds and their use...

1999-01-22

2001-07-03

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S104000, C526S170000, C526S154000, C526S943000, C526S348000, C502S117000, C502S152000, C502S155000

Reexamination Certificate

active

06255418

ABSTRACT:

The present invention relates to a class of organochromium catalysts formed by a reaction of donor ligand substituted &eegr;
5
-organyl chromium complexes with Lewis acids, which have a high catalytic activity in the polymerization and copolymerization of alkenes.
It is known that transition metal compounds with amido-substituted cyclopentadienyl ligands, above all with Ti (e.g., X) catalyze alkene polymerization in the presence of methylaluminoxane (MAO) [K. B. Sinclair and R. B. Wilson, Chem. Ind. 857 (1994); Dow Chemicals, Eur. Pat. 416 815 (1991); Exxon Chemicals, Eur. Pat. 420 436 (1991)], but corresponding systems with a donor ligand of group 15 (N, P, As, Sb, Bi) of the Periodic Table as a substituent have not been reported to date.
Surprisingly, it has now been found that organochromium compounds of general formula (I) can be employed in the polymerization and copolymerization of alkenes in the presence of Lewis acids, such as organyl compounds of boron or aluminum, e.g., methylaluminoxane:
wherein R
1
contains a delocalized &eegr;
5
-coordinated &pgr; system, such as cyclopentadienyl, indenyl, fluorenyl;
X is an electronegative atom or group, such as halide or amide, or an organyl group, such as alkyl or aryl, or CrX
2
is a metallacyclic fragment, such as
Y is a donor atom of group 15 (N, P, As, Sb, Bi) of the Periodic Table;
Z is an atom of group 14 (C, Si, Ge, Sn, Pb) of the Periodic Table;
R′ are H, organyl groups;
R″ are H, organyl groups; and
n≧1.
Typical Examples are compounds (II)-(IX); Table 1 defines the substituents R
1
, R′, R″ and X, Y and Z (Cy represents cyclohexyl, Me represents methyl, and Et represents ethyl). The molecular structures of the novel compounds VI and IX were determined by X-ray crystallography and represented in
FIGS. 1 and 2
, respectively.
TABLE 1
Typical organochromium compounds
Compound No.
X
Y
Z
n
R
1
R′
R″
II
Cl
N
C
2
C
5
Me
4
H
Me
III
C
2
H
4
a
N
C
2
C
5
Me
4
H
Me
IV
Cl
N
C
2
indenyl
H
Me
V
I
N
C
2
C
5
Me
4
H
Me
VI
Cl
P
C
2
C
5
H
4
H
cyclohexyl
VII
Me
P
C
2
C
5
H
4
H
cyclohexyl
VIII
Cl
N
Si
1
C
5
H
4
Me
Et
IX
Me
N
C
2
C
5
Me
4
H
C
2
H
4
b


The organochromium compounds are obtained in high yields by the reaction of a Cr trihalide with a metal salt of the corresponding donor ligand substituted &eegr;
5
-organyl derivative, e.g.:
wherein the resulting Cr dihalide derivatives can be used as the starting compounds for the preparation of further examples, e.g.:
 VI+
2
LiMe→VII+
2
LICl
Activating those compounds with Lewis Acids results in highly active catalysts for alkene polymerization and copolymerization. Preferred alkenes are &agr;-alkenes, while ethene is preferred in the copolymerization with strained alkenes. Examples 9-15 deal with ethene, Examples 16 and 17 with propene, and Example 18 with copolymerization. The reaction may be performed in aromatic solvents (toluene) or saturated hydrocarbons (n-heptane), at room temperature (20-30° C.) and low pressures (2 bar). Surprisingly, the full catalytic activity is achieved with an Al:Cr molar ratio of 45-300:1 already. In contrast, the Ti based system X and the Zr containing ansa-metallocenes, e.g., XI [M. Aulbach and F. Küber, Chem. unser. Zeit 28, 197 (1994)], required Al:metal ratios of about 10
4
:1.
In the presence of MAO, the novel Cr compounds, preferably compounds VII and IX, catalyze the polymerization of ethene to give highly linear polyethylene having a bimodal molecular weight distribution (Table 3). In addition, homologous alkenes, such as propene, can also be polymerized (atactic polypropylene), and ethene, for example, can be copolymerized with norbornene. In the latter case, an almost purely alternating copolymer (XII) is generated which contains 43% of norbornene and 57% of ethene as determined by
13
C NMR, and exclusively has exo configurations at the bicyclic ring.


REFERENCES:
patent: 4015059 (1977-03-01), Karol
patent: 5418200 (1995-05-01), Carney et al.
patent: 4431838 (1996-03-01), None
patent: 0416815 (1991-03-01), None
patent: 0682037 (1995-11-01), None
patent: 0 416 815 (1996-05-01), None
patent: 9411410 (1994-05-01), None
patent: WO 96/13529 (1996-05-01), None
Organometallics, Band 16, Nr. 8, Apr. 1997, Rainer Emerich, et al., The Role of Metallacycles . . . Ethylene, pp. 1511-1513.
Organometallics, Band 15, 1996, Yuanfeng Liang et al., Constrained . . . Polymerization, pp. 5284-5286.

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