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Title:
POLYMERISATION OF ETHYLENE AND ALPHA-OLEFINS WITH PYRROLIMINOPHENOL COMPLEXES.
Document Type and Number:
WIPO Patent Application WO/2008/061901
Kind Code:
A1
Abstract:
The present invention relates to the field of single site catalyst systems based on pyrrol-iminophenol, pyrrol-iminoalcohol or pyrrol-iminoamine complexes and suitable for oligomerising or homo- or co-polymerising ethylene and alpha-olefins.

Inventors:
HILLAIRET, Caroline (Rue du Nouveau Monde 64, Soignies, B-7060, BE)
MICHAUD, Guillaume (308 Rue Nationale, Lille, Lille, F-59000, FR)
SIROL, Sabine (rue I. Vanschepdael 37, Wauthier-braine, B-1440, BE)
Application Number:
EP2007/062112
Publication Date:
May 29, 2008
Filing Date:
November 09, 2007
Export Citation:
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Assignee:
TOTAL PETROCHEMICALS RESEARCH FELUY (Zone Industrielle C, Seneffe, B-7181, BE)
HILLAIRET, Caroline (Rue du Nouveau Monde 64, Soignies, B-7060, BE)
MICHAUD, Guillaume (308 Rue Nationale, Lille, Lille, F-59000, FR)
SIROL, Sabine (rue I. Vanschepdael 37, Wauthier-braine, B-1440, BE)
International Classes:
C07F19/00; C07F7/00; C07F11/00
Domestic Patent References:
WO1998042665A11998-10-01
WO2004081020A12004-09-23
Foreign References:
EP1426385A12004-06-09
DD99556A11973-08-12
EP1574529A12005-09-14
EP1426385A12004-06-09
Other References:
TAYIM H. A. ET AL.: "Reactions of 2-Pyrrole-[N-(o-Hydroxyphenyl]aldimine] with Metal Ions", POLYHEDRON, vol. 5, no. 3, 1986, pages 691 - 693, XP002431024
DATABASE CA [online] CHEMICAL ABSTRACTS SERVICE, COLUMBUS, OHIO, US; BASU, SEMANTI ET AL: "Rhodium and iridium complexes of N-(2'-hydroxyphenyl)pyrrole-2- aldimine: Synthesis, structure, and spectral and electrochemical properties", XP002431026, retrieved from STN Database accession no. 2005:350893
GIBSON, V.C.; SPITZMESSER, S.K., CHEM. REV., vol. 103, 2003, pages 283
SAWUSCH, N. JAGER; U. SCHILDE; E. UHLEMANN, STRUCTURAL CHEMISTRY, vol. 10, no. 2, 1999, pages 105
BASU, SEMANTI; PAL, INDRANI; BUTCHER, RAY J.; ROSAIR, GEORGINA; BHATTACHARYA, SAMARESH, JOUMAL OF CHEMICAL SCIENCES, vol. 117, no. 2, 2005, pages 167
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Claims:

CLAIMS

1. A metallic complex of formula I

(I)

wherein R 1 , R 2 , R3, R4, R5, Re, R7, Rs, Rg, R10, Rn and R 12 are each independently selected from hydrogen, unsubstituted or substituted hydrocarbyl having from 1 to 20 carbon atoms, or inert functional group and wherein two or more of those groups can be linked together to form further ring or rings; wherein M is a metal Group 3 to 10 of the Periodic Table; wherein Y is O or NR*, with R* being alkyl or aryl group having from 1 to 12 carbon atoms; wherein each X is the same or different and is selected from halogen; wherein m is zero or an integer from 1 to 3; wherein (n+2) is the valence of M; and wherein

R"

is either

or

2. The metallic complex of claim 1 wherein m is zero and R2, R3, R 4 , Rs, Rθ and R 11 are the same and are hydrogen.

3. The metallic complex of claim 1 or claim 2 wherein R 1 , R 5 , R 6 , R7, R10 and R12 are each independently selected from hydrogen, substituted or unsubstituted alkyl or aryl groups, halogen, nitro or cyano groups.

4. The metallic complex of any one of claims 1 to 3 wherein at least one of Ri, Re and R 7 or Ri, R10 and R12 is not hydrogen.

5. The metallic complex of any one of the preceding claims wherein M is Ti, Cr, Zr or Fe.

6. The metallic complex of any one of the preceding claims wherein X is Cl.

7. A method for preparing the metallic complex of any one of claims 1 to 6 by reacting a ligand of formula Il

( H )

with a metallic salt MX n+ 2 in a solvent, wherein R 1 , R 2 , R3, R4, R5, Re, R7, Rs, Rg R10, Rnand R 12 , M, X, Y, m, n, and R" are as described in any one of claims 1 to 6.

8. An active catalyst system comprising the metallic complex of any one of claims 1 to 6, an activating agent selected from an aluminium- or boron-containing complex and optionally a cocatalyst.

9. An active catalyst system comprising the catalyst component of any one of claims 1 to 6, an activating support and optionally a cocatalyst.

10. A method for preparing the active catalyst system of claim 8 or claim 9 that comprises the steps of: a) providing the metallic complex of any one of claims 1 to 6 ; b) activating with an activating agent having an ionising action or with an activating support; c) optionally adding a cocatalyst; d) retrieving an active oligomerisation or polymerisation catalyst system.

11. A method for oligomerising or homo- or co-polymerising ethylene and alpha- olefins that comprises the steps of: a) injecting the active catalyst system of claim 8 or claim 9 into the reactor; b) injecting the monomer and optional comonomer into the reactor either before or after or simultaneously with step a); c) maintaining under polymerisation conditions; d) retrieving the oligomers or polymer.

12. The method of claim 11 wherein the monomer and optional comonomer are selected from ethylene, propylene and 1 -hexene.

Description:

POLYMERISATION OF ETHYLENE AND ALPHA-OLEFINS WITH PYRROL-

IMINOPHENOL COMPLEXES.

The present invention relates to the field of single site catalyst systems based on pyrrole-iminophenol, pyrrole-iminoalcohol or pyrrole-iminoamine complexes and suitable for oligomerising or polymerising ethylene and alpha-olefins.

A multitude of catalyst systems available for polymerising or oligomerising ethylene and alpha-olefins exist, but there is a growing need for finding new systems capable of tailoring polymers with very specific properties. More and more post-metallocene catalyst components based on early or late transition metals from Groups 3 to 10 of the Periodic Table have recently been investigated such as for example those disclosed in Gibson and al. review (Gibson, V. C; Spitzmesser, S. K., in Chem. Rev. 2003, 103, p. 283).

Pyrrol-iminophenol derivatives are known and have been described for example by Schilde (Sawusch, N. Jager, U. Schilde and E. Uhlemann in Structural Chemistry, Vol. 10, No. 2, 1999 p. 105), Bhattacharya (Basu, Semanti; Pal, Indrani; Butcher, Ray J.; Rosair, Georgina; Bhattacharya, Samaresh in Journal of Chemical Sciences, 2005, 117(2), p. 167) but corresponding complexes have never been described as catalysts for the polymerisation of olefins.

There is still a need to improve either the specificities or the performances of these systems.

It is an aim of this invention to provide new single site catalysts based on thdentate pyrrol-iminophenol, pyrrol-iminoalcohol or pyrrol-iminoamine.

It is another aim of the present invention to provide active catalyst systems based on these catalyst components.

It is a further aim of the present invention to provide a process for polymerising or for oligomerising ethylene and alpha-olefins with these new catalyst systems.

Any one or more of these aims is fulfilled, at least partially, by the present invention.

Accordingly, the present invention discloses metallic complexes of formula I

(I)

wherein Ri, R 2 , R3, R 4 , R5, Re, R7, Rs, R9, R10, Rn and R12 are each independently selected from hydrogen, unsubstituted or substituted hydrocarbyl having from 1 to 20 carbon atoms, or inert functional group. Two or more of those groups can themselves be linked together to form further ring or rings; wherein M is a metal Group 3 to 10 of the Periodic Table; wherein Y is O or NR*, with R* being alkyl or aryl group having from 1 to 12 carbon atoms; wherein each X can be the same or different and is selected from halogen, substituted or unsubstituted hydrocarbyl having from 1 to 20 carbon atoms, substituted or unsubstituted aryloxy or alkoxy; wherein m is zero or an integer from 1 to 3; wherein (n+2) is the valence of M; and wherein

R"

is either

or

The metallic complex results from the complexation of a ligand of general formula Il with metallic salt MX n+ 2 in a solvent

( H )

wherein Ri to R12, M, X, R" and m are as described hereabove.

Ligand of formula Il is the reaction product of carbonylated pyrrole of formula III with compound of formula IV or IV,

(Hi)

(IV)

or

(IV)

wherein Ri to R12 and m are as described hereabove.

The reaction conditions are well known in the art.

By inert functional group, is meant a group, other than hydrocarbyl or substituted hydrocarbyl, that is inert under the complexation conditions to which the compound containing said group is subjected. They can be selected for example from halo, ester, ether, amino, imino, nitro, cyano, carboxyl, phosphate, phosphonite, phosphine, phosphinite, thioether and amide. Preferably, they are selected from halo, such as chloro, bromo, fluoro and iodo, or ether of formula - OR * wherin R * is unsubstituted or substituted hydrocarbyl. After metallation of the ligand, an inert functional group must not coordinate to the metal more strongly than the groups organised to coordinate to the metal and thereby displace the desired coordinating group.

In preferred embodiments according to the present invention, m is zero and R2, R3, R 4 , R 8 , Rg and Rn are hydrogen and Ri, R 5 , Re, R7, R10 and R12 can each be independently selected from hydrogen, substituted or unsubstituted hydrocarbyl having from 1 to 20 carbon atoms, halogen, nitro or cyano groups.

In this description, substituted hydrocarbyls are defined as chains or links that may comprise one or more heteroatoms.

Preferably, Ri, R 5 , Re, R7, R10 and R12 are each independently selected from hydrogen or substituted or unsubstituted alkyl or aryl groups or halogen.

The preferred alkyl groups are methyl and tert-butyl.

The preferred aryl groups are unsubstituted or substituted phenyl groups.

The preferred halogen is chlorine.

Preferably all three Ri, Re and R 7 are not hydrogen simultaneously.

More preferably either R 6 or R 7 is present, the other being hydrogen, and Ri is hydrogen or one of the preferred substituent groups described hereabove.

Preferably M is Ti, Zr, Hf, V, Cr, Mn, Fe, Co, Ni, Pd or rare earths. More preferably, it is Ti, Cr, Fe or Zr.

Preferably X is halogen, more preferably it is chlorine.

The solvent may be selected from dichloromethane or tetrahydrofuran and the complexation reaction is carried out at room temperature or at reflux.

The present invention further discloses an active catalyst system comprising the single site catalyst component of formula I or I' and an activating agent having an ionising action.

Suitable activating agents are well known in the art. The activating agent can be an aluminium alkyl represented by formula AIR + n X3 -n wherein R + is an alkyl having from 1 to 20 carbon atoms and X is a halogen. The preferred alkylating agents are triisobutyl aluminium (TIBAL) or triethyl aluminium (TEAL).

Alternatively, it can be aluminoxane and comprise oligomeric linear and/or cyclic alkyl aluminoxanes represented by formula

R -- (Al -O) n -Al R * 2

R*

for oligomeric, linear aluminoxanes and by formula

R*

for oligomeric, cyclic aluminoxane,

wherein n is 1-40, preferably 10-20, m is 3-40, preferably 3-20 and R * is a d-C 8 alkyl group and preferably methyl.

The amount of activating agent is selected to give an Al/M ratio of from 100 to 3000, preferably of from 500 to 2000. The amount of activating agent depends upon its nature: for IBAO the preferred Al/M ratio is of about 500, and for MAO, it is about 2000.

Suitable boron-containing activating agents may comprise a thphenylcarbenium boronate such as tetrakis-pentafluorophenyl-borato-triphenylcarbenium as described in EP-A-0427696, or those of the general formula [L'-H] + [B An Ar 2 X3 X4]- as described in EP-A-0277004 (page 6, line 30 to page 7, line 7). The amount of boron -containing activating agent is selected to give B/M ratio of from 0.5 to 5, preferably of about 1.

In another embodiment, according to the present invention, the single site catalyst component of formula I may be deposited on a conventional support. Preferably, the conventional support is silica impregnated with MAO. Alternatively and preferably, it can be an activating support such as fluorinated alumina silica.

The present invention further discloses a method for preparing an active catalyst system that comprises the steps of: a) providing a ligand of formula Il or II'; b) complexing the ligand of step a) with a metallic salt MX n+ 2 in a solvent; c) retrieving catalyst component I or I'; d) activating the catalyst component of step c) with an activating agent having an ionising action; e) optionally adding a cocatalyst; f) retrieving an active oligomerisation or polymerisation catalyst system.

Alternatively, in step d) catalyst component I or I' is deposited on a support impregnated with an activating agent or on a fluor containing activating support.

The cocatalyst may be selected from thethylaluminium, triisobutylaluminum, tris-n- octylaluminium, tetraisobutyldialuminoxane or diethyl zinc.

The active catalyst system is used in the oligomerisation and in the polymerisation of ethylene and alpha-olefins.

The present invention discloses a method for the oligomerisation or the homo- or co- polymerisation of ethylene and alpha-olefins that comprises the steps of: a) injecting the active catalyst system into the reactor; and b) injecting the monomer and optional comonomer either before or after or simultaneously with step a); c) maintaining under polymerisation conditions; d) retrieving the oligomers and/or polymer.

The pressure in the reactor can vary from 0.5 to 50 bars, preferably from 5 to 25 bars.

The polymerisation temperature can range from 10 to 100 0 C, preferably from 50 to 85°C.

Preferably the monomer and optional comonomer are selected from ethylene, propylene or 1-hexene.

In another preferred embodiment according to the present invention, the optional comonomer is a polar functional ised alpha-olefin.

Examples.

All reactions were performed using standard Schlenk techniques or in an argon-filled glove-box. The starting materials and reagents, purchased from commercial suppliers, were used without purification. All the solvents were dried and distilled before use either over sodium and benzophenone for toluene, pentane and THF, or over CaH 2 for ethanol. 1 H, 13 C NMR spectra were recorded on a Bruker Advance300 apparatus.

Preparation of ligands.

I. Ligands.

General procedure.

2 mmol of 2-pyrrolcarboxaldehyde (reagent 1 ) and 2 mmol of 2-aminophenol (reagent 2) were dissolved in 10 ml_ of dry ethanol. One drop of glacial acetic acid was added and the reaction mixture was stirred during 12h. The solution was filtered and the solid was washed with 3ml of dry ethanol. Ligands were obtained as a solid.

Synthesis of ligand 2-(pyrrolyl-methyleneimino)-phenol (L1 ).

Ligand L1 was prepared following the general procedure and 2-amino-phenol was used as reagent 2. Ligand L1 was obtained with a yield of 92 %.

1 H NMR (300 MHz, DMSO d6) δ (ppm): 6.21 (s, 1 H), 6.69 (s, 1 H), 6.79-6.87 (m, 2H), 7.02 (m, 1 H), 7.13 (s, 1 H), 7.33 (d, J=9Hz, 1 H), 8.55 (s, 1 H), 8.78 (bs, 1 H), 11.80 (s, 1 H).

Synthesis of I igand 2-(pyrrolyl-methyleneimino)-4-methyl -phenol (L2)

Ligand L2 was prepared following the same procedure as that used to prepare ligand L1 except that 2-amino-4-methyl-phenol was used as reagent 2. Ligand L2 was obtained with a yield of 94 %.

1 H NMR (300 MHz, DMSO d6) δ (ppm): 2.21 (s, 3H), 5.75 (s, 1 H), 6.65 (d, J=3Hz, 1 H), 6.73 (d, J=9Hz, 1 H), 6.82 (d, J=3Hz, 1 H), 7.16 (d, J=9Hz, 2H), 8.54 (bs, 2H), 11.78 (s, 1 H).

Synthesis of ligand 2-(pyrrolyl-methyleneimino)-5-methyl-phenol (L3).

Ligand L3 was prepared following the same procedure as that used to prepare ligand L1 except that 2-amino-5-methyl-phenol was used as reagent 2. Ligand L3 was obtained with a yield of 93 %.

1 H NMR (300 MHz, DMSO d6) δ (ppm): 2.22 (s, 3H), 6.20 (s, 1 H), 6.50-6.80 (m, 3H), 7.11 (s, 1 H), 7.23 (d, J=9Hz, 1 H), 8.52 (s, 1 H), 8.66 (s, 1 H), 11.74 (s, 1 H).

Synthesis of ligand 2-( pyrrolyl-methyleneimino)-4-tertbutyl-phenol (L4).

Ligand L4 was prepared following the same procedure as that used to prepare ligand L1 except that 2-amino-4-tertbutyl-phenol was used as reagent 2. Ligand L4 was obtained with a yield of 90 %.

1 H NMR (300 MHz, DMSO d6) δ (ppm): 1.26 (s, 9H), 6.20 (s, 1 H), 6.66 (s, 1 H), 6.78 (d, J=9Hz, 1 H), 7.05 (d, J=9Hz, 1 H), 7.11 (s, 1 H), 7.32 (s, 1 H), 8.61 (s, 2H), 11.77 (s, 1 H).

Synthesis of ligand 2-(pyrrolyl-methyleneimino)-4-chloro-phenol (L5).

Ligand L5 was prepared following the same procedure as that used to prepare ligand L1 except that 2-amino-4-chloro-phenol was used as reagent 2. Ligand L5 was obtained with a yield of 97 %.

1 H NMR (300 MHz, DMSO d6) δ (ppm): 6.22 (s, 1 H), 6.69 (s, 1 H), 6.85 (d, J=9Hz, 1 H), 7.05 (d, J=9Hz, 1 H), 7.16 (s, 1 H), 7.40 (s, 1 H), 8.58 (s, 1 H), 8.97 (s, 1 H), 11.82 (s, 1 H).

Synthesis of ligand 2-(pyrrolyl-methyleneimino)-4-phenyl-phenol (L6).

Ligand L6 was prepared following the same procedure as that used to prepare ligand L1 except that 2-amino-4-phenyl-phenol was used as reagent 2. Ligand L6 was obtained with a yield of 93 %.

1 H NMR (300 MHz, DMSO d6) δ (ppm): 6.22 (s, 1 H), 6.69 (s, 1 H), 6.94 (d, J=9Hz, 1 H), 7.15 (s, 1 H), 7.28-7.65 (m, 7H), 8.73 (s, 1 H), 8.90 (s, 1 H), 11.82 (s, 1 H).

Synthesis of ligand 2-(pyrrolyl-methyleneimino)-3-methyl-phenol (L7).

Ligand L7 was prepared following the same procedure as that used to prepare ligand L1 except that 2-amino-3-methyl-phenol was used as reagent 2. Ligand L7 was obtained with a yield of 99 %.

1 H NMR (300 MHz, DMSO d6) δ (ppm): 2.15 (s, 3H), 6.18 (s, 1 H), 6.77-6.59 (m, 4H), 7.01 (s, 1 H), 8.22 (s, 1 H), 9.0 (bs, 1 H), 11.65 (s, 1 H).

Synthesis of ligand 2-(pyrrolyl-methyleneimino)-4-nitro-phenol (L8).

Ligand L8 was prepared following the same procedure as that used to prepare ligand L1 except that 2-amino-4-nitro-phenol was used as reagent 2. Ligand L8 was obtained with a yield of 92 %.

1 H NMR (300 MHz, DMSO d6) δ (ppm): 6.25 (s, 1 H), 6.78 (d, J=3Hz, 1 H), 7.03 (d, J=9Hz, 1 H), 7.20 (s, 1 H), 7.96 (d, J=9Hz, 1 H), 8.18 (d, J=3Hz, 1 H), 8.69 (s, 1 H), 10.12 (bs, 1 H), 11.84 (s, 1 H).

13 C{ 1 H} NMR (75 MHz, DMSO c/6) δ (ppm): 110.7, 113.2, 115.8, 118.0, 122.9, 125.2, 131.3, 137.5, 140.5, 150.6, 158.7.

II. Preparation of metallic complexes.

Synthesis of titanium Ti(IV) complexes.

1 mmol of ligand was dissolved in 5 ml_ of THF and cooled to a temperature of - 78°C. 2 mmol of n-butyl lithium (1.6 M in hexane) was added drop-wise. The solution was stirred for 2 hours at room temperature. 1 mmol of TiCI 4 (1 M in toluene) was dissolved in 5 ml_ of THF and cooled to a temperature of -78°C. The solution of the anionic ligand was added drop-wise to the solution of TiCI 4 . The resulting solution was stirred overnight at room temperature. The mixture was evaporated to dryness and the complex was extracted with 10 ml_ of dry dichloromethane. The filtrate was evaporated and the residue was washed with 3 ml_ of diethyl ether, with 10 ml_ of pentane, and with another 10 ml_ of pentane. The resulting solid was dried under vacuum to afford metallic complex as powder.

Ligand L1 was used to prepare complex A1 with a yield of 82 %.

Ligand L2 was used to prepare complex A2 with a yield of 91 %.

Ligand L3 was used to prepare complex A3 with a yield of 90 %.

Ligand L4 was used to prepare complex A4 with a yield of 90 %

Ligand L5 was used to prepare complex A5 with a yield of 93%.

Ligand L6 was used to prepare complex A6 with a yield of 90 %.

Ligand L7 was used to prepare complex A7 with a yield of 47 %.

Ligand L8 was used to prepare complex A8 with a yield of 42%.

Synthesis of chromium Cr(III) complexes.

1 mmol of ligand was dissolved in 5 mL of THF and cooled to a temperature of - 15°C. 2 mmol of n-butyl lithium (1.6 M in hexane) was added drop-wise. The solution

was stirred for 30 minutes and added to a solution of 1 mmol of (THF) 3 CrCIs dissolved in 5 ml_ of THF. The resulting solution was stirred overnight at room temperature. The mixture was concentrated to approximately 2 ml_ and 10 ml_ of pentane were added. Solvents were filtered off and the solid was washed twice with pentane. The resulting solid was dried under vacuum to afford metallic complex as a powder.

Ligand L1 was used to prepare complex B1 with a yield of 99 %.

Ligand L2 was used to prepare complex B2 with a yield of 91 %.

Ligand L3 was used to prepare complex B3 with a yield of 92%.

Ligand L4 was used to prepare complex B4 with a yield of 99%.

Ligand L5 was used to prepare complex B5 with a yield of 99%.

Ligand L6 was used to prepare complex B6 with a yield of 93%.

Ligand L7 was used to prepare complex B7 with a yield of 93%.

Ligand L8 was used to prepare complex B8 with a yield of 97%.

Synthesis of zirconium Zr(IV) complexe.

1 mmol of ligand L1 was dissolved in 5 mL of THF and cooled to a temperature of - 78°C. 2 mmol of n-butyl lithium (1.6 M in hexane) was added drop-wise. The solution was stirred for 2 hours at room temperature. 1 mmol of ZrCI 4 was dissolved in 5 mL of THF and cooled to a temperature of -78°C. The solution of the anionic ligand was added drop-wise to the solution of ZrCI 4 . The resulting solution was stirred overnight at room temperature. The mixture was evaporated to dryness and the complex was

extracted with 10 ml_ of dry dichloromethane. The filtrate was evaporated and the residue was washed with 3 ml_ of diethyl ether, with 10 ml_ of pentane, and with another 10 ml_ of pentane. The resulting solid was dried under vacuum to afford complex C1 as powder with 71 % yield.

C1

Synthesis of vanadium V(III) complexe.

1 mmol of ligand L1 was dissolved in 5 ml_ of THF and cooled to a temperature of - 78°C. 2 mmol of n-butyl lithium (1.6 M in hexane) was added drop-wise. The solution was stirred for 2 hours at room temperature. 1 mmol of (THF) 3 VCl3 was dissolved in 5 ml_ of THF and cooled to a temperature of -78°C. The solution of the anionic ligand was added drop-wise to the solution of VCI3. The resulting solution was stirred overnight at room temperature. The mixture was evaporated to dryness and the complex was extracted with 10 ml_ of dry dichloromethane. The filtrate was evaporated and the residue was washed with 3 ml_ of diethyl ether, with 10 ml_ of pentane, and with another 10 ml_ of pentane. The resulting solid was dried under vacuum to afford complex D1 as powder with 72% yield.

III. Polymerisation of ethylene.

Polymerisation reactions were realised on a 24 parallel reactor unit containing glass inserts of 50 ml with magnetic stirrers. In a glove box, 0.5 mg of metallic complex were introduced into a vial. Then 0.6 ml of methylaluminoxane (MAO) (30 wt% in

toluene) and 24 ml of heptane were added. The vials were crimped with a septum and installed into the reactor unit heated at a temperature of 60 0 C. The vials' septa were pierced by the needles of the reactor unit. Stirring was started and regulated at a speed of 1000 rpm. Then ethylene was injected and the pressure was regulated at 22 bar while the temperature was increased to 80 0 C. These conditions were maintained during 30 min., then the reactors were depressurised and cooled down. The vials were opened and an acidic alcoholic solution was added. The polymers were filtered, washed and dried. The results are displayed in Table I.

TABLE I.

a 20 min. instead of 30 min. b 1.2 ml of MAO instead of 0.6 ml c 1.5 ml of MAO instead of 0.6 ml

IV. Polymerisation of ethylene with a supported catalyst system.

Complex A8 was deposited on a MAO impregnated silica (Sylopol 952X1836), with 2.2 wt % of complex based on the total weight of the obtained supported catalyst. This supported catalyst was used for the polymerisation of ethylene. Ethylene polymerisation reactions were carried out in a 130 ml stainless steel autoclave equipped with mechanical stirring and a stainless steel injection cylinder. In a typical reaction run, the reactor was first dried under nitrogen flow at 100 0 C during 10 min. Then it was cooled down to the reaction temperature of 85°C, and 35 ml of

isobutane were introduced into the reactor with a syringe pump, followed by the comonomer if required. The pressure was adjusted to the desired value of 29 bars, with ethylene. In an argon-filled glove box, 100 mg of the supported catalyst, 0.29 ml of TiBAI (10% in n-hexane) and 0.5 ml of n-heptane were placed into the injection cylinder. The valve was closed and the cylinder was connected to the reactor under nitrogen flow. The active catalyst mixture was then introduced into the reactor with 40 ml of isobutane. After 1 hour at 750 rpm, the reactor was cooled down to room temperature and slowly depressurised. The polymer was recovered and characterised by DSC. The polymerisation results are displayed in Table II.

TABLE II.

Activity is expressed as g of polyethylene per g of supported catalyst per hour.

Due to the high molecular weight of the obtained polymers, GPC analysis were not possible, even in TCB at 135°C.