Note: Descriptions are shown in the official language in which they were submitted.
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Stereorigid, Bridged Metallocene Catalysts for
Polyolefin Production
Field of the Invention
The present invention relates to a metallocene catalyst
component for use in preparing polyolefins, especially
polypropylenes. The invention further relates to a catalyst
system which incorporates the metallocene catalyst component
and a process for preparing such polyolefins.
Background to the Invention
Olefins having 3 or more carbon atoms can be polymerised to
produce a polymer with an isotactic stereochemical
configuration. For example, in the polymerisation of
propylene to form polypropylene, the isotactic structure is
typically described as having methyl groups attached to the
tertiary carbon atoms of successive monomeric units on the
same side of a hypothetical plane through the main chain of
the polymer. This can be described using the Fischer
projection formula as follows:
{ I f I I i I
Another way of describing the structure is through the use of
NMR spectroscopy. Bovey's NMR nomenclature for an isotactic
pentad is ... rrimmm with each "m" representing a"meso" diad
or successive methyl groups on the same side in the plane.
In contrast to the isotactic structure, syndiotactic polymers
are those in which the methyl groups attached to the tertiary
carbon atoms of successive monomeric units in the chain lie
on alternate sides of the plane of the polymer. Using the
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Fischer projection formula, the structure of a syndiotactic
polymer is described as follows:
In NMR nomenclature, a syndiotactic pentad is described as
...rrrr... in which "r" represents a "racemic" diad with
successive methyl groups on alternate sides of the plane.
In contrast to isotactic and syndiotactic polymers, an
atactic polymer exhibits no regular order of repeating unit.
Unlike syndiotactic or isotactic polymers, an atactic polymer
is not crystalline and forms essentially a waxy product.
While it is possible for a catalyst to produce all three
types of polymer, it is desirable for a catalyst to produce
predominantly an isotactic or syndiotactic polymer with very
little atactic polymer. C2-symmetric metallocene catalysts
are known in the production of the polyolefins. For example,
C2 symmetric bis indenyl type zirconocenes which can produce
high molecular weight high melting isotactic polypropylene.
The preparation of this metallocene catalyst is costly and
time-consuming, however. Most importantly, the final
catalyst consists of a mixture of racemic and meso isomers in
an often unfavourable ratio. The meso stereoisomer has to be
separated to avoid the formation of atactic polypropylene
during the polymerisation reaction.
EP-A-0426644 relates to syndiotactic copolymers of olefins
such as propylene obtainable using as a catalyst component
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isopropyl (fluorenyl)(cyclopentadienyl) zirconium dichloride.
Syndiotacticity, as measured by the amount of syndiotactic
pentads, rrrr was found to be 73-80%.
EP 747406 relates to the polymerisation of an olefin monomer
to form a syndiotactic/isotactic block polyolefin,
particularly a block polypropylene. A component of the
polymerisation catalyst was a 3-trimethylsilyl
cyclopentadienyl-9-fluorenyl zirconium or hafnium dichloride
having an isopropylidene or diphenylmethylidene bridge.
EP-A-0537130 discloses the use of a Cl symmetric metallocene
catalysts for the production of isotactic polypropylene. A
preferred catalyst is isopropylidine (3-tert butyl-
cyclopentadienyl-fluorenyl) ZrC12. This catalyst has a bulky
t-butyl group positioned on the cyclopentadienyl ring distal
to the isopropylidine bridge. This catalyst has the
advantage that it consists of only one stereoisomer and so no
isomeric metallocene separation is required at the final
stage of its synthesis. Whilst polypropylene preparation
using this catalyst produces isotactic polypropylene, the
polymer product has poor mechanical properties because of the
presence of regiodefects and relatively low molecular weight.
Regiodefects occur in the polymer chain when, instead of
producing a perfect isotactic polyolefin in which each
monomeric unit is positioned head-to-tail in relation to the
next, mis-insertions of the monomers occur so as to give
either a head-to-head or tail-to-tail mis-match. These so
called (2-1) regiodefects are partially transferred to the so
called (1-3) insertion through an isomerisation process
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leaving units of four CH2 groups in the backbone of the
polypropylene chain. This has a deleterious effect on the
physical and mechanical properties of the polymer and results
in low molecular weight isotactic polypropylene with a low
melting point. EP-A-0881236 addresses this problem by
providing isopropylidene (5-methyl-3t-butyl cyclopentadienyl
fluorene) zirconium dichloride as part of a polymerisation
catalyst. However, polypropylenes obtained using this
catalyst have molecular weights (Mw) in the range 213900 to
458500 and a microtacticity characterised by the mmmm pentad
in the range 82.8% to 86.8%. The melting temperature of
these polymers is in the range 139.3 to 143.8.
EP-A-577581 discloses the production of syndiotactic
polypropylenes using metallocene catalysts which have
fluorenyl groups substituted in positions 2 and 7 and an
unsubstituted cyclopentadienyl ring. The production of
isotactic or syndiotactic/isotactic block polyolefins using
these metallocene catalysts is not disclosed.
EP-A-0748824 describes the use of a chiral transition metal
compound and an aluminoxane to produce stereoregular
isotactic polypropylenes with a reported isotactic pentad
content of up to 0.972. No data are presented in relation to
the amount of monomer misinsertions in the polypropylene.
Summary of the Invention
The present invention aims to overcome the disadvantages of
the prior art.
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In a first aspect, the present invention provides use of a
metallocene catalyst component for the preparation of a
polyolefin which comprises an isotactic or polyolefin
syndiotactic/isotactic block polyolefin having a monomer
length of up to C10, which component has the general formula:
R" (CpRiR2 R3 )(cp' Ri' R2' ) MQ2 ( I)
wherein Cp is a cyclopentadienyl ring substituted with at
least one substituent; Cp' is a substituted fluorenyl ring;
R" is a structural bridge imparting stereorigidity to the
component; R1 is optionally a substituent on the
cyclopentadienyl ring which is distal to the bridge, which
distal substituent comprises a bulky group of the formula
XR*3 in which X is chosen from Group IVA, and each R* is the
same or different and chosen from hydrogen or hydrocarbyl of
from 1 to 20 carbon atoms, R2 is optionally a substituent on
the cyclopentadienyl ring which is proximal to the bridge and
positioned non-vicinal to the distal substituent and is of
the formula YR#3 in which Y is chosen from group IVA, and
each R# is the same or different and chosen from hydrogen or
hydrocarbyl of 1 to 7 carbon atoms, R3 is optionally a
substituent on the cyclopentadienyl ring which is proximal to
the bridge and is a hydrogen atom or is of the formula ZR$3,
in which Z is chosen from group IVA, and each R$ is the same
or different and chosen from hydrogen or hydrocarbyl of 1 to
7 carbon atoms, R1' and R2' are each independently substituent
groups on the fluorenyl ring, one of which is a group of the
formula AR "'3r in which A is chosen from Group IVA, and each
R"' is independently hydrogen or a hydrocarbyl having 1 to
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20 carbon atoms and the other is hydrogen or a second group
of the formula AR "'3; M is a Group IVB transition metal or
vanadium; and each Q is hydrocarbyl having 1 to 20 carbon
atoms or is a halogen.
Polyolefins produced using the metallocene catalyst component
of the present invention are surprisingly found to have very
good microtacticity, especially as determined by pentad
distribution levels in 13C nmr. The polyolefins are also
found to be substantially free of regiodefects. Accordingly,
the polyolefins produced thereby have improved mechanical
properties including a high weight average molecular weight
typically in excess of 500,000 and melting point elevated by
at least 10 C as compared with prior art values.
The applicants have unexpectedly found that if in the
metallocene catalysts the fluorenyl ring is substituted in
certain specific positions, preferably in position 3 and/or
6, there is a significant improvement in the tacticity of the
produced polymer, and a dramatic drop in the regio-defects of
said polymer.
According to the present invention, the fluorenyl ring may be
substituted by radicals of general formula: AR "'3 where A is
preferably carbon or silicon and is more preferably carbon.
Where A is carbon, AR "' may be a hydrocarbyl selected from
alkyl, aryl, alkenyl, alkyl aryl or aryl alkyl, such as
methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl,
isoamyl, hexyl, heptyl, octyl, nonyl, decyl, cetyl or phenyl.
Where A is silicon, AR "'3 may be Si(CH3)3. Preferably at
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least one of R'l and R'2 is t-butyl. More preferably both
R'l and R'2 are the same.
In addition, the applicants have also found that when
catalysts of the invention are used to produce polypropylene,
they show melting points generally higher than 150 C and
which may even reach 165 C which is a considerable
improvement over the prior art.
The structural bridge R" is preferably alkylidene having 1 t
20 aliphatic or aromatic carbon atoms, a dialkyl germanium o
silicon or siloxane, alkyl phosphene or amine bridging the
two Cp rings. R" is preferably isopropylidene in which the
two Cp rings are bridged at position 2 of the isopropylidene.
Alternatively, R" is diphenylmethylidene.or dimethylsilanediyl.
M is preferably zirconium or titanium, most preferably
zironium. Q may be a hydrocarbyl such as alkyl, aryl,
alkenyl, alkylaryl or aryl alkyl, preferably methyl, ethyl,
propyl, isopropyl, butyl, isobutyl, amyl, isoamyl, hexyl,
heptyl, octyl, nonyl, decyl, cetyl or phenyl. Q is
preferably a halogen..
The selection of the substitution pattern on the
cyclopentadienyl ring depends on the desired stereochemistry
of the polyolefin product. The metallocene catalyst
component of the present invention may be used to produce
isotactic polyolefins or syndiotactic/isotactic block
polyolefins. The polyolefins can be homopolymers or
copolymers. Where a syndiotactic/isotactic polyolefin is
required, it is preferred that the cyclopentadienyl ring is
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substituted at a position distal to the bridge. R1 is
therefore not hydrogen but is instead a substituent on the
cyclopentadienyl ring. It is preferred that Rl is a bulky
distal substituent group.
In the bulky distal substituent group R1, X is preferably C
or Si. R* may be a hydrocarbyl such as alkyl, aryl, alkenyl,
alkylaryl or aryl alkyl, preferably methyl, ethyl, propyl,
isopropyl, butyl, isobutyl, amyl, isoamyl, hexyl, heptyl,
octyl, nonyl, decyl, cetyl or phenyl. Rl may comprise a
hydrocarbyl which is attached to a single carbon atom in the
cyclopentadienyl ring or may be bonded to two carbon atoms in
that ring. Preferably, R1 is C(CH3)3, C(CH3)2Ph, CPh3 or
Si(CH3)3, most preferably C(CH3)3.
Where an isotactic polyolefin is required, it is preferred
that both Rl and R2 are not hydrogen. R2 is a substituent on
the cyclopentadienyl ring which is proximal to the bridge and
preferably comprises a CH3 group.
The cyclopentadienyl ring may also be substituted by R3 in
isotactic polyolefin production. R3 is preferably CH3.
In a further aspect, the metallocene catalyst component for
use in preparing polyolefins comprises (i) a catalyst
component as defined above; and (ii) a regioisomer thereof in
which R2 is proximal to the bridge and positioned vicinal to
the distal substituent.
Such regioisomers are frequently relatively easy to prepare
because they are formed as a "by-product" during the
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synthetic route by which the catalyst component (i) may be
made.
Surprisingly, it has been found that catalyst components
including both regioisomers can be used in the preparation of
polyolefins which have a multimodal, especially a bimodal,
molecular weight distribution.
In a further aspect, a catalyst system is used for preparing
the polyolefins, which system comprises (a) a catalyst
component as defined above; and (b) an aluminium- or boron-
containing cocatalyst capable of activating the catalyst
component. Suitable aluminium-containing cocatalysts
comprise an alumoxane, an alkyl aluminium and/or a Lewis
acid.
The alumoxanes usable in the process of the present invention
are well known and preferably comprise oligomeric linear
and/or cyclic alkyl alumoxanes represented by the formula:
( I ) R- (Al-0)q-A1R2
for oligomeric, linear alumoxanes and
(II) (-Al -O- ~n
for oligomeric, cyclic alumoxane,
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wherein n is 1-40, preferably 10-20, m is 3-40, preferably 3-
20 and R is a C1-C8 alkyl group and preferably methyl.
Generally, in the preparation of alumoxanes from, for
example, aluminium trimethyl and water, a mixture of linear
and cyclic compounds is obtained.
Suitable boron-containing cocatalysts may comprise a
triphenylcarbenium boronate such as tetrakis-
pentafluorophenyl-borato-triphenylcarbenium as described in
EP-A-0427696, or those of the general formula [L'-H] + [B Arl
Ar2 X3 X4]- as described in EP-A-0277004 (page 6, line 30 to
page 7, line 7).
The catalyst system may be employed in a solution
polymerisation process, which is homogeneous, or a slurry
process, which is heterogeneous. In a solution process,
typical solvents include hydrocarbons with 4 to 7 carbon
atoms such as heptane, toluene or cyclohexane. In a slurry
process it is riecessary to immobilise the catalyst system on
an inert support, particularly a porous solid support such as
talc, inorganic oxides and resinous support materials such as
polyolefin. Preferably, the support material is an inorganic
oxide in its finally divided form.
Suitable inorganic oxide materials which are desirably
employed in accordance with this invention include Group 2a,
3a, 4a or 4b metal. oxides such as silica, alumina and
mixtures thereof. Other inorganic oxides that may be
employed either alone or in combination with the silica, or
alumina are magnesia, titania, zirconia, and the like.
Other suitable support materials, however, can be employed,
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for example, finely divided functionalized polyolefins such
as finely divided polyethylene.
Preferably, the support is a silica having a surface area
comprised between 200 and 700 m2/g and a pore volume
comprised between 0.5 and 3 ml/g.
The amount of alumoxane and metallocenes usefully employed in
the preparation of the solid support catalyst can vary over a
wide range. Preferably the aluminium to transition metal
mole ratio is in the range between 1:1 and 100:1, preferably
in the range 5:1 and 50:1.
The order of addition of the metallocenes and alumoxane to
the support material can vary. In accordance with a
preferred embodiment of the present invention alumoxane
dissolved in a suitable inert hydrocarbon solvent is added to
the support material slurried in the same or other suitable
hydrocarbon liquid and thereafter a mixture of the
metallocene catalyst component is added to the slurry.
Preferred solvents include mineral oils and the various
hydrocarbons which are liquid at reaction temperature and
which do not react with the individual ingredients.
Illustrative examples of the useful solvents include the
alkanes such as pentane, iso-pentane, hexane, heptane, octane
and nonane; cycloalkanes such as cyclopentane and
cyclohexane, and aromatics such as benzene, toluene,
ethylbenzene and diethylbenzene.
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Preferably the support material is slurried in toluene and
the metallocene and alumoxane are dissolved in toluene prior
to addition to the support material.
In a further aspect, the present invention provides use of a
catalyst component as defined above and a cocatalyst which
activates the catalyst component, for the preparation of
polyolefins, preferably polypropylenes. Although the present
invention is dedicated to the use of metallocene catalysts,
the fluorenyl ring of which has preferably been substituted
in positions 3 and/or 6, it has been noted that by using a
metallocene catalyst component comprising (i) the catalyic
component and (ii) a regioisomer thereof, in which R2 is
proximal to the bridge and positioned vicinal to the distal
substituent, for the preparation of polyolefins, especially
polypropylenes, having a multimodal molecular weight
distribution, preferably a bimodal molecular weight
distribution.
In a further aspect, the present invention provides a process
for preparing polyolefins, especially polypropylenes, which
comprises contacting a catalyst system as defined above with
at least one olefin, preferably propylene, in a reaction zone
under polymerisation conditions.
The catalyst component may be prepared by any suitable method
known in the art. Generally, the preparation of the catalyst
component comprises forming and isolating bridged
dicyclopentadiene, which is then reacted with a halogenated
metal to form the bridged metallocene catalyst.
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In one embodiment, the process for preparing the bridged
metallocene catalyst components comprises contacting the
cyclopentadiene with a substituted fluorene under reaction
conditions sufficient to produce a bridged dicyclopentadiene.
The process further comprises contacting the bridged
substituted dicyclopentadiene with a metal compound of the
formula MQk as defined above under reaction conditions
sufficient to complex the bridged dicyclopentadiene to
produce a bridged metallocene wherein M and Q are each
defined as above and 0<_ k_ 4. The process step of
contacting the bridged substituted dicyclopentadiene with a
metal compound can be performed in a chlorinated solvent.
In a further embodiment, the process comprises contacting the
cyclopentadiene with an alkyl silyl chloride of the formula
R-2 Si Ha12 wherein R- is a hydrocarbyl having 1 to 20 carbon
atoms and Hal is a halogen. A second equivalent of a
substituted fluorene is added to produce a silicon bridged
cyclopentadienyl-substituent fluorenyl ligand. The
subsequent steps are similar to those above for producing a
bridged substituted cyclopentadienyl-fluroenyl ligand
coordinated to metals such as Zr, Hf and Ti..
In a further embodiment, the process comprises contacting the
substituted cyclopentadiene with a fulvene producing agent
such as acetone to produce a substituted fulvene.
Subsequently, in a second step, the fulvene is reacted with a
fluorene substituted in position 3 and/or 6, and preferably
both 3 and 6, to produce a carbon bridged substituted
cyclopentadienyl-fluorenyl ligand that will produce the
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desired metallocene catalysts after reacting with MC14, in
which M is Zr, Hf or Ti.
In a further aspect, the present invention provides an
isotactic polyolefin having a monomer length of up to C10 and
a pentad distribution comprising greater than 80% and
preferably at least 87% mmmm as measured by 13C nmr. The
pentad distribution preferably comprises at least 90%, more
preferably at least 95% mmmm as measured by 13C nmr.
Preferably, the amount 2-1 and 1-3 monomer insertions in the
polyolefin is less than 0.5%, more preferably, less than 0.2
and most preferably undetectable typically as measured by 13C
nmr.
The invention will now be described in further detail, by way
of example only, with reference to the attached drawings in
which:
FIGURES 1 to 12 show illustrations of the structures of
preferred catalyst components of the present invention; and
FIGURE 13 shows the results of differential scanning
calorimetry analysis on isotactic polypropylene produced at
40 C using the catalyst shown in Figure 1.
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Example 1
Preparation of isopropylidene [(3-tertbutyl-5-methyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)] zirconium
dichloride
A. Preparation of 3,6,6-trimethylfulvene
Reaction
Methanol
Me-Cp + Acetone ----------- > 3, 6, 6-Me3-Ful
Pyrolidene
Procedure
In a round bottom flask equipped with magnetic stirring bar
and N2 inlet is placed 350 ml of methanol (at -78 C)
containing freshly prepared methylcyclopentadiene under N2.
To this solution is added a solution of 28.6 g (0.493 mol) of
acetone in 50 ml of methanol dropwise. Subsequently 52.5 g
(0.738 mol) of pyrolidene is added. The reaction mixture is
stirred at ambient temperature for 24 hours. After
neutralisation with acetic acid and separation of the organic
phase the solvent is evaporated and the remaining yellow oil
is subjected to distillation. A mixture of 3,6,6-Me3-Ful and
2,6,6-Me3-Ful is obtained in 65% yield.
B. Preparation of 1-methyl-3-tert-butylcyclopentadiene
Reaction
Ether
3,6,6-Me3-Ful + Me-Li ------------ l-Me-3-t-Bu-Cp
0 C
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Procedure
50 g (0.417 mol) of 3,6,6-Me3-t-Bu-Ful is placed in a 1 litre
flask and dissolved in 500 ml of diethyl ether and cooled
down to 0 C. To the solution is added dropwise 260.4 ml
(0.417 mol) of methyllithium in ether (1.6 mol). The
reaction is completed after a few hours. After adding 75 ml
of saturated solution of NH4C1 in water, the organic phase is
separated and dried with MgSO4. The evaporation of the
solvent leads to the isolation of a yellow oil. After
distillation, 33.65 g(59.280) of 1-Me-3-t-Bu-Cp is obtained.
C. Preparation of 1,6,6-trimethyl-3-tert-butylfulvene
Reaction
Methanol
1-Me-3-t-Bu-Cp + Acetone ---------> 1,6,6-Me3-3-t-Bu-Ful
Pyrolidene
Procedure
In a 1 1 flask is placed 30 g (0.220 mol) of 1-Me-3-t-Bu-Cp
and dissolved in 60 ml of methanol. The mixture is cooled
down to -78 C. 5.11 g (0.088 mol) of acetone in 20 ml of
methanol is added slowly. In the next step, 9.4 g(0.132
mol) of pyrolidene in 20 ml of methanol is added. After a
week, the reaction is terminated by addition of 20 ml of
acetic acid. After separation of the organic phase, drying,
evaporation of solvents and distillation, 16.95 g of an
orange oil is obtained (yield, 43.66%).
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D. Preparation of 2,2-[(3-tertbutyl-5-methyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]-propane
Reaction
THF
3,6-d-t-Bu-Flu + Me-Li ---------- (3,6-d-t-Bu-Flu)-Li+
0 C
THF
(3, 6-d-t-Bu-Flu) -Li+ + 1, 6, 6-Me3-3-t-Bu-Ful --- > Me2C(3-t-Bu-
5-Me-Cp)(3,6-d-t-Bu-Flu)
Procedure
1.5 g (5.387 mmol) of 3,6-d-t-Bu-Flu in 100 ml of dry
tetrahydrofuran, is placed into a 250 ml flask, under N2 and
the solution is pre-cooled to 0 C. The 3,6-d-t-Bu-Flu may be
synthesised according to Shoji Kajigaeshi et al. Bull. Chem.
Soc. Jpn. 59,97-103(1986) or M Bruch et al. Liebigs Ann.
Chem. 1976,74-88. Then, a solution of 3.4 ml (5.387 mmol) of
methyllithium is added drop wise to the solution. The
solution is red and is further continued at room temperature
during 4 hours. After that, a solution of 0.9497 g (5.382
mmol) of 1,6,6-Me3-3-t-Bu-Ful in 10 ml of dry tetrahydrofuran
is added dropwise to this solution. The reaction is further
continued during 24 hours. After adding 40 ml of saturated
solution of NH4C1 in water, the yellow organic phase is
separated and dried with MgS04 anhydrous. The evaporation of
the solvent leads to the isolation of 2.36 g (yield, 96.32%)
of orange solid product.
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E. Preparation of isopropylidene [(3-tertbutyl-5-methyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)] zirconium
dichloride (1)
Reaction
THF
Me2C(3-t-Bu-5-Me-Cp)(3,6-d-t-Bu-Flu) + 2 Me-Li --->
0 C
Me2C(3-t-Bu-5-Me-Cp)-Li+(3,6-d-Bu-Flu)-Li+
ZrC14
Me2C(3-t-Bu-5-Me-Cp)-Li+(3,6-d-t-Bu-Flu)-Li+ ---->
n-C5
Me2C(3-t-Bu-S-Me-Cp)(3,6-d-t-Bu-Flu)ZrCl2 + 2 LiCl
Procedure
2 g (4.398 mmol) of ligand is dissolved in 100 ml of dry
tetrahydrofuran under N2, and the solution is pre-cooled to
0 C. A solution of 5.5 ml (8.796 mmol) of methyllithium (1.6
mol/diethyl ether) is added dropwise to this solution. After
3 hours, the solvent is removed in vacuum, the red powder is
washed with 2 x 100 ml of pentane. The red dianion ligand
and 100 ml of pentane are placed into a 250 ml flask, under
N2. 1.02 g (4.398 mmol) of zirconium tetrachloride is added
to this suspension. The reaction mixture is red-brown and
stirred overnight in a glove box. After filtration, the
orange solution is removed in vacuo at 40 C and yielded 2.3 g
(85.18%) of orange powder. Apparently, this metallocene is
soluble in pentane. According the 1HNMR of the product it
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seems that a second isomer with a chemical structure of
isopropylidene (2(or 4)-methyl-3-tertbutylcyclopentadienyl-
3,6-ditertbutylfluorenyl)ZrC12 (2) is formed as the second
product which is less stereoregular.
Example 2
Preparation of isopropylidene [(3-methyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)] zirconium
dichloride
The synthetic procedure according to Example 1 is followed
except that the ligand in step D is replaced by the 2,2-[(3-
methyl-cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]-
propane.
A. Preparation of 2,2-[(3-methyl-cyclopentadienyl)-(3,6-di-
tertbutyl-fluorenyl)]-propane
Procedure
The preparation of this ligand is the same as that of step D,
but the 1,6,6-trimethyl-3-tert-butylfulvene is replaced by
0.6475 g (5.387 mmol) of 3,6,6-trimethylfulvene (the
synthetic procedure is described in Example 1, step A).
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Example 3
Preparation of isopropylidene [(3-tertbutyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)] zirconium
dichloride
The synthetic procedure according to Example 1 is followed
except that the ligand in step D is replaced by the 2,2-[(3-
tertbutyl-cyclopentadienyl)-(3,6-di-
tertbutyl-fluorenyl)]-propane prepared as below.
A. Preparation of 2,2-[(3-tertbutyl-cyclopentadienyl)-(3,6-
di-tertbutyl-fluorenyl)]-propane
Procedure
The preparation of this ligand is the same that the step D,
but the 1,6,6-trimethyl-3-tert-butylfulvene is replaced by
0.8742 g (5.387 mmol) of 6,6-dimethyl-3-tert-butylfulvene.
B. Preparation of 6,6-dimethyl-3-tert-butylfulvene
Procedure
The synthetic procedure according to Example 1, step A, is
followed, but the methylcyclopentadiene is replaced by the
tert-butylcyclopentadiene.
C. Preparation of tert-butylcyclopentadiene
Procedure
The synthetic procedure according to Example 1, step B, is
followed, but the 3, 6, 6-trimethylfulvene is replaced by 6,6-
dimethylfulvene.
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Example 4a
Preparation of isopropylidene[(3-trimethylsilyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]zirconium
dichloride
The synthetic procedure according to Example 1 is followed
except that the ligand in step D is replaced by the
diphenyl[(3-trimethylsilyl-cyclopentadienyl)-(3,6-di-
tertbutyl-fluorenyl)]methylene.
A. Preparation of 2,2-[(3-trimethylsilyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]propane
Procedure
The preparation of this ligand is the same as described in
Example 1, step D, except that the 1,6,6-trimethyl-3-tert-
butylfulvene is replaced by 1.2407 g (5.387 mmol) of 6,6-
dimethylfulvene.
B. Preparation of 2,2-[(3-trimethylsilyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]propane
Reaction
THF
Me2C(Cp)(3,6-d-t-Bu-Flu) + Me-Li --~
Me2C(Li+Cp-)(3,6-d-t-Bu-Flu)
Me2C(Li+Cp-)(3,6-d-t-Bu-Flu) + Me3Si-Cl ---->
Me2C(3-Me3Si-Cp)(3,6-d-t-Bu-Flu) + LiCl
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Procedure
First, in a 1 1 flask, 10 g (0.026 mol) of 2,2-
(cyclopentadienyl)(3,6-di-tertbutyl-fluroenyl)propane is
dissolved in 300 ml of tetrahydrofuran under N2. Then 16.25
ml (0.026 mol) of methyllithium is added dropwise to this
solution at room temperature (the flask is pre-cooled with a
water bath) After a stirring period of one hour, 3.3 ml
(0.026 mol) of chlorotrimethylsilane, is added to this
solution. The reaction mixture is stirred for an additional
3 hours. Then the solvent is removed in vacuo. One litre of
pentane is added to the solid orange residue. the reaction
mixture is heated at 40 C for 10 minutes. The orange
solution is filtered (to remove LiCl, 1.40 g of residue),
concentrated to 100 ml, and cooled down to crystallise the
product 2,2-(3-trimethylsilyl-cyclopentadienyl)
fluorenyl)propane. The raw product has a beige colour. The
crystallised product has a white colour, 65-70% yield. The
product was stored under N2.
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Example 4b
Preparation of diphenylmethylidene[(3-trimethylsilyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]zirconium
dichloride
The synthetic procedure according to Example 1 is followed
except that the ligand in step D is replaced by the
diphenyl[(3-trimethylsilyl-cyclopentadienyl)-(3,6-di-
tertbutyl-fluorenyl)]methylene.
A. Preparation of 1,1,1,1-diphenyl[(3-trimethylsilyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]methane
Procedure
The preparation of this ligand is the same as described in
Example 1, step D, except that the 1,6,6-trimethyl-3-tert-
butylfulvene is replaced by 1.2407 g (5.387 mmol) of 6,6-
dimethylfulvene.
B. Preparation of diphenyl[(3-trimethylsilyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]methane
Reaction
THF
Me2C(Cp)(3,6-d-t-Bu-Flu) + Me-Li --~
Me2C(Li+Cp-)(3,6-d-t-Bu-Flu)
Me2C(Li+Cp-)(3,6-d-t-Bu-Flu) + Me3Si-Cl ----~
Me2C(3-Me3Si-Cp)(3,6-d-t-Bu-Flu) + LiCl
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Procedure
First, in a 1 1 flask, 10 g (0.026 mol) of 2,2-
(cyclopentadienyl)(3,6-di-tertbutyl-fluorenyl)propane is
dissolved in 300 ml of tetrahydrofuran under N2. Then 16.25
ml (0.026 mol) of methyllithium is added dropwise to this
solution at room temperature (the flask is pre-cooled with a
water bath) After a stirring period of one hour, 3.3 ml
(0.026 mol) of chlorotrimethylsilane, is added to this
solution. The reaction mixture is stirred for an additional
3 hours. Then the solvent is removed in vacuo. One litre of
pentane is added to the solid orange residue. the reaction
mixture is heated at 40 C for 10 minutes. The orange
solution is filtered (to remove LiCl, 1.40 g of residue),
concentrated to 100 ml, and cooled down to crystallise the
product 2,2-(3-trimethylsilyl-cyclopentadienyl) (3,6-di-
tertbutyl fluorenyl)propane. The raw product has a beige
colour. The crystallised product has a white colour, 65-70%
yield. The product was stored under N2.
Example 5
Preparation of isopropylidene[(3,5-dimethyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)] zirconium
dichloride
The synthetic procedure according to Example 1 is followed
except that the ligand in step D is replaced by the 2,2-
[(3,5-dimethyl-cyclopentadienyl)-(3,6-di-tertbutyl-
fluorenyl)]-propane.
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A. Preparation of 2,2-[(3,5-dimethyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]-propane
Procedure
The preparation of this ligand is the same as in Example 1
step D, but the 1,6,6-trimethyl-3-tert-butylfulvene is
replaced by 0.8742 g (5.387 mmol) of 1,3,6,6-
tetramethylfulvene.
B. Preparation of 1,3,6,6-tetramethylfulvene
The synthetic procedure according to Example 1 step A, is
followed but the methylcyclopentadiene is replaced by 1,3-
dimethylcyclopentadiene.
C. Preparation of 1,3-dimethylcyclopentadiene
Reaction
Ether
3-Me-Cp=O + CH3-Mg-Br ------~ 1,3-Me2-Cp-0-Mg-Be
0 C
1,3-Me2-Cp-O-Mg-Br + H20 -----~ 1,3-Me2-Cp + Mg-Br-OH
Procedure
195 ml (0.585 mole) of methyl magnesium bromide (solution 3.0
mole/diethyl ether) in 200 ml of dry diethyl ether, is placed
into a 2 1 flask, under N2 and the solution is pre-cooled to
0 C. Then a solution of 47.15 g (0.4905 mole) of 3-methyl-2-
cyclopentenone in 100 ml of diethyl ether is added dropwise
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to the solution for 3 hours at 0 C and for an hour at 10 C.
This product is transferred into a 5 1 flask pre-cooled to
0 C and containing 1 1 of water. The solution is yellow.
The yellow organic phase is separated and the solvent is
removed in vacuo (500 mbars) at room temperature. The
evaporation of the solvent leads to the isolation of a clear
orange solution. After distillation 31.83 g (yield, 65.95%)
of 1,3-dimethylcyclopentadiene is obtained. The product is a
colourless unstable liquid and used directly for the
preparation of the 1,3,6,6-trimethylfulvene.
Example 6
Preparation of diphenylmethylidene[(3-methyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)] zirconium
dichloride
The synthetic procedure according to Example 1 is followed
except that the ligand in step D is replaced by the 2,2-
diphenyl[(3-methyl-cyclopentadienyl)-(3,6-di-tertbutyl-
fluorenyl)]propane.
A. Preparation of 1,1,1,1-diphenyl[(3-methyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)methane
Procedure
The preparation of this ligand is the same as described in
Example 1, step D, except that the 1,6,6-trimethyl-3-tert-
butylfulvene is replaced by 1.2407 g (5.387 mmol) of 3-
methyl-6,6-diphenylfulvene.
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B. Preparation of 3-methyl-6,6-diphenylfulvene
Procedure
The preparation of this fulvene is the same as described in
Example 1, step A, except that the acetone is replaced by
1.3162 g (5.387 mmol) of 6,6-diphenylfulvene.
Example 7
Preparation of diphenylmethylidene[(3-tertbutyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)] zirconium
dichloride
The synthetic procedure according to Example 1 is followed
except that the ligand in step D is replaced by the
diphenyl[(3-terbutyl-cyclopentadienyl)-(3,6-di-tertbutyl-
fluorenyl)]methylene.
A. Preparation of 1,1,1,1-diphenyl[(3-tertbutyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]methane
Procedure
The preparation of this ligand is the same as described in
Example 4, step A, except that the 6,6-dimethyl-3-tert-
butylfulvene is replaced by the 3-tertbutyl-6,6-
diphenylfulvene.
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B. Preparation of 3-tertbutyl-6,6-diphenylfulvene
Procedure
The preparation of this fulvene is the same as described in
Example 1, step A, except that the acetone is replaced by the
benzophenone and the methylcyclopentadiene is replaced by the
tert-butylcyclopentadiene (the synthetic procedure is
described in Example 4, step C).
Example 8
Preparation of diphenylmethylidene[(3-trimethylsilyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)] zirconium
dichloride
The synthetic procedure according to Example 1 is followed
except that the ligand in step D is replaced by the 2,2-
diphenyl[(3-trimethylsilyl-cyclopentadienyl)-(3,6-di-
tertbutyl-fluorenyl)]propane
A. Preparation of 1,1,1,1-diphenyl[(3-trimethylsilyl-
cyclopentadienyl)-(3,6-di-tertbutyl-fluorenyl)]methane
Procedure
The preparation of this ligand is the same as described in
Example 4, step B, except that the 2,2-
[(cyclopentadiene)(fluorenyl)]propane is replaced by the 2,2-
diphenyl[(cyclopentadienyl)(fluorenyl)]propane.
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B. Preparation of 2,2-diphenyl[(cyclopentadienyl)-(3,6-di-
tertbutyl-fluorenyl)]propane
Procedure
The preparation of this ligand is the same as described in
Example 1, step D, except that the 1,6,6-trimethyl-3-tert-
butylfulvene is replaced by the 6,6-diphenylfulvene.
Example 9
Polymerisation procedures
Each polymerisation was performed in a 4 litre bench reactor
with pure propylene. Polymerisation was initiated by
introducing metallocene (0.5 to 5 mg) precontacted with 1 ml
of MAO (methylaluminoxane) (30% solution in toluene obtained
from WITCO) three minutes prior to its introduction into the
reactor.
Table 1 shows the microtacticity of the polymer obtained
using the catalyst according to Example 1 under
polymerisation conditions as defined above. The results were
obtained using 13C NMR spectroscopy. It will be apparent that
the polypropylene contained more than 95% of pentads in the
purely isotactic form (mmmm). The molecular weight (Mw) of
the polypropylene was 530,000 and the melting point was
153 C. Melting point was determined by DSC analysis as shown
in Figure 13. A sample was held at 25 C for 1 min, heated
from 25 C to 220 C at 20 C/min and held for 5 mins at 220 C.
The sample was then cooled from 220 C to 25 C at 20 C/min,
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held at 25 C for 3 mins and heated from 25 C to 220 C at
20 C/min.
Table 1
Pentad stereo-sequence distributions %
mmmm 95.7
mmmr 1.70
rmmr 0.00
mmrr 1.70
mrmm 0.00
+ rmrr
mrmr 0.00
rrrr 0.00
mrrr 0.00
mrrm 0.80
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6p r-> u-> 1- co C) 0 0 ckO
N r-I C) rl -4 rl M ~-I tl) M l0 C)
~ lfl lfl V' lfl Ln r
61 61 61 6l 6l m 6l ~l 61 61 61 61
N co 1-0 ' M 1-I Q0 lo N O
Q M M (M (N M N [- cn N M M cM
c--1 OC) l0 (M Ln 00 00 O cn
M rl O OJ l0 O ~' 0) OC) 61
N H k.0 (D N I'D CX) CD 1- Y' C) lfl
01 M
l0 OC) N I- Oo lfl L- ~T N l-
M 61 r-i l0 O N l- O M
r-I N O ~' M tl) tn I- ~-I O O [-
N l- . . N . . ,
61 ~--I I- N Ln O O
M a 6l M [- [- ~-- N N
OJ 1-0 M O 61 O M C) ri OC) Ln M
QO klO O
O lfl Ll tn r l0 M Ol d' C OC)
tt~ l- r-I -I M 00 lfl 61 Ol
= d' Ln Ln N ~ N CM '-I LC)
3 3 N ~o 0
O M N OC) ri r--i N N l- un (Y) -I
N 00 lfl Ln -I C) M T) l- [- ~-I O
lfl ~-I O 01 N N O 01 co l0 N M
O N 1-1 O [- Ol lfl ~' ~ 01 M Ol
Ln Ln Ol [~ rl 00 l0 M r-I ~ l0
~=1
N
U rn k-0 o r rn rn (N -i Ln
U . . .
f1 O Ln ~t' N N Q0
rl r-I ri C) ~-i (D ri r-1 ~--~
E-1 ~-i -i ~-I r--1 r-I rl r-i 1-i r-1
N d~ Ln 00 ~v [- u) rn N t- Ln
,~ . . . .
o ~ ~n rn o U
~ ~ ~ ~ Ln Ln Ln Lr) ~-o "D
H
O oC) o v~
Ln Q0 1-1
4-1 Ul 61 N Ol Ln l0 l~ O 01 Ul
=r=I Ol OC) l- Un [- M Ln
O O O
N 00 [- CD -i tf~ ~-1 ~.7~ l0 Ql
=r~ . . . . . . . . . ~'
4-t -i a' Ln r ~1 ~ ~ ~o ~n 41
~
~ -i 1-1 (N N M (N
Lf) Ol [- O p
N o 00
-1 Ln
0 O 4-3 0
={ H H H H H H H H H U p H H H
zz z ~ b z z z
~ O O O C) O C) O e-1 N -P >1 o o r-i
W
o o
O D U U U U U U U U ~ 0
a o O O O O O O O O a O~ O~ O~
0 0 0 0 0 0 0 0 0 o 0 0
H QO Q0 kJO ao Qo 00 -0 H Q0 "0 Q0
$4
a)
a -
~
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Table 2 shows further examples of the production of isotactic
polypropylene using the catalyst according to Example 1 under
the polymerisation conditions defined above. It will be
apparent that the isotactic propylene produced contained in
some cases over 97% of pentads in the purely isotactic form
(mmmm). High weight average molecular weights were obtained
at 40 C and 60 C, particularly in the absence of added
hydrogen. A polymerisation temperature of around 60 C was
found to be particularly useful because relatively high
molecular weights and high catalyst activity were obtained in
combination with good microtacticity.
